Reef Ramblings

24/6/2012

An intriguing new theory suggests that seagrass growing in the immediate vicinity of a coral reef may be able to mitigate ocean acidification.

Research

Research due to be published as a paper in the Open Access Environmental Research Letters journal, found that the high photosynthetic rates of seagrass meadows can make seawater less acidic and potentially enhance the growth of nearby corals, helping to preserve the world’s most beautiful and fragile coral reefs from extinction due to ocean acidification.

The research was conducted by Dr Richard Unsworth, Research Officer at the Centre for Sustainable Aquatic Research, College of Science, Swansea University in collaboration with scientists at the University of Oxford, the Northern Fisheries Centre, Australia, and James Cook University in Australia.

Explaining the background to the study Dr Unsworth said: “Highly productive tropical seagrasses often live adjacent to or among coral reefs and photosynthesise at such rates you can see the oxygen they produce practically bubbling away. We wanted to understand whether this could be a major local influence on seawater and the problems of ocean acidification.”

Rising atmospheric carbon dioxide (CO2) in the air, primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. Over long-term timescales, this change in seawater carbonate chemistry is likely to cause coral reefs to start to disappear as the rate of erosion starts to exceed growth rates. Coral reefs house thousands of unique species that are found nowhere else on the planet. They provide physical protection for small island communities, and provide food for millions of people globally. Losing these reefs would have serious negative economic and food security consequences.

Dr Unsworth explained that their research models have shown remarkable results. He said: “Our analyses show that in shallow water reef environments coral calcification downstream of seagrass has the potential to be 18% greater than in an environment without seagrass. It illustrates the importance of keeping seagrass meadows healthy and offers a potential tool in marine park management to offset the impacts of ocean acidification (depending on local conditions and habitats)”. He added “Not only are seagrass meadows important to hundreds of millions of people worldwide who are dependent upon the food resources that they supply, our novel study suggests that they could potentially, in the long-term, have the added benefit of enhancing the growth of coral reefs under threat of extinction”.

Adapted from material on the Swansea University website.

A Poor Show from the BBC

The BBC is normally excellent when reporting science stories, but when covering this story managed to miss-describe corals as being, “… worm-like creatures of around a centimetre length which live in colonies numbering millions…”

In the Reef Aquarium

The rise in pH described by the researchers can also occur under aquarium conditions. If macro algae start to proliferate to the extent that it grows out of control it can result in pH increasing values of 9 and higher. Remember that the pH scale is logarithmic so a reading of say 9.2 is ten times more alkaline than the more usual reef aquarium value of 8.2. The higher the pH value, the greater the toxicity of any free ammonia that’s present. To correct this problem add CO2 to the system until the pH drops to the correct value. The various CO2 reactors designed for CO2 fertilization in the freshwater-planted aquarium are ideal for this purpose. Follow this up by harvesting excess macro algae until balance is restored and CO2 is no longer needed.

Tim Hayes

Midland Reefs

©2012

Cyanobacteria outbreaks in the marine aquarium are nearly always the result of inadequate husbandry, it’s a problem that builds up steadily over time before manifesting itself as a wine red bio-film on the substrate, rockwork, and eventually, even on corals. Over time, excess nutrients introduced into the aquarium through feeding and the addition of various supplements, build up to become a potential reserve ready to fuel outbreaks of cyanobacteria and pest algae. Overfeeding, overstocking with fish, inadequate amounts of live rock, inadequate filtration, and poor maintenance are all factors, which can contribute to cyanobacteria and pest algae outbreaks. Poor flow and lighting issues are also often implicated in cyano outbreaks but may be considered a trigger rather than the cause.

In addition to cyano being unsightly, depending on species, it can produce various forms of toxins, which can be detrimental to corals on contact, toxins detrimental to fishes, and may also deplete oxygen levels in the aquarium.

Treating Cyanobacteria with DrTim’s Re-Fresh and Waste-Away.

Treating Cyanobacteria with DrTim’s Re-Fresh and Waste-Away is a two-pronged approach that works in more than 90% of cases. It’s a completely natural process using bacteria and, unlike antibiotics or chemicals, there is no danger of killing off beneficial microorganisms, such as nitrifying bacteria. Not only does this treatment cure the symptoms but it also goes along way towards eliminating the source of the problem, something other treatments don’t do (See note at the end of article).

Re-Fresh is the initial treatment, a potent combination of beneficial bacteria that work together to maintain clear water, clean aquarium surfaces and eliminate unpleasant odours. If cyano is out of control in your aquarium and you’re at wits end – use it! However, it will not cure the problem, it only treats the symptoms just like other cyano products. By following-up with Waste-Away you go after the factors causing cyanobacteria, nutrients such as organics, nitrate and phosphate, ending up with a complete cure.

Waste-Away is an innovative, special blend of bacteria isolated from our own freshwater and saltwater aquaria and ponds. These bacteria attack organics, both dissolved and particulate, in the aquarium and in the process consume phosphate and nitrate. As mentioned organics, nitrate and phosphate fuel growth of algae, slime and cyanobacteria so using antibiotics/algaecides will only temporally help. And once they kill their target the dead algae and cyanobacteria decay producing more organics and nutrients to feed more algae and cyanobacteria – continuing the cycle.

Go Natural – Stop Using Chemicals and Antibiotics!

Using DrTim’s Aquatics Waste-Away as a 100% Natural way to get rid of the underlying cause of out of control growth of aquarium slime, algae and cyanobacteria. These unsightly organisms grow when nutrients and organics are high in your aquarium. The only long-term way to deal with them is to eliminate their food – excess nutrient and organics.

How to get rid of algae and cyanobacteria.

The outdated methods of using antibiotics and algaecides have one ‘benefit’ – they work fast. You can usually see results in a day. But this ‘victory’ is short lived and the cyanobacteria or algae come back even stronger than before because, as mentioned earlier, the decaying dead cells become food that spurs the re-growth of the algae and cyanobacteria. The 100% natural alternative method presented here takes a little longer but does not involve any harmful chemicals or antibiotics just beneficial bacteria that get to the source of the problem.

Here’s how to proceed:

1) Manually remove as much of the algae/cyano as possible by siphoning, netting and micro filtration.

2) Use DrTim’s Re-Fresh for a total of 9 to 12 days adding Re-Fresh every 3 to 4 days (dosage is 5 ml per 40 litres aquarium water). While dosing with Re-Fresh you should notice a difference,  you’ll start see that the cyano is not coming back,  that’s the time to hit it one more time with Re-Fresh before starting with waste-away.

Reef tank owners – Do Not Overdose: high doses of Re-Fresh may harm snails and shrimp.

3) After the Re-Fresh regime, dose the aquarium with Waste-Away. Start with a half-dose (5ml per 10 gallons). Add another half dose 2 days later. If there are a lot of organics in the system you may experience cloudy water. This is a sign that the beneficial bacteria are working but also a sign to proceed cautiously because too much of a bacterial bloom can lower the oxygen to dangerous levels. If there is no cloudiness add a full dose on day 4.

Continue to add Waste-Away every 2 to 3 days (watching for any cloudiness) for 2 weeks. Generally at the end of this 4 week period of adding Re-Fresh and Waste-Away the tank will be clean and there will be a noticeable improvement in water clarity, cleanliness of the substrate, and no cyanobacteria

Once the aquarium is looking better we recommend adding Waste-Away on a routine basis – at least every month for a reef tank and every 2-3 weeks for a fish-only tank.

The above works! Click here to see testimonials from professionals

Waste-Away can do the job of clearing cyanobacteria on its own, just omit step 2, the Re-Fresh stage, and dose with Waste-Away every 2 to 3 days but it will take longer before you see results.

Note: it is important for you to evaluate the reasons for the organic build-up in the aquarium in the first place. Is it the result of overfeeding, over-population, lack of routine cleaning? To save you continued headaches a critical self-evaluation of the causes is warranted and action needed.

Tim Hayes

Midland Reefs

Dr Tim Hovanec

DrTim’s Aquatics

©2011

Over the next week I’ll be adding a new section to Reef Ramblings, entitled Fish Disease. This will cover both freshwater and saltwater.

I’m grateful to Dr. John Shawn Prescott, for allowing me to publish his series of articles about fish disease on Reef Ramblings. Based on articles written for a leading USA magazine, as well as some lectures, from when the author was an active member of the EAFP (European Assoc. of Fish Pathologists), they deal with most of the common parasitic, bacterial, and viral diseases, that occur in fresh and salt water aquaria.

This series makes a good starting point for the hobbyist wanting a better understanding of fish disease and how to treat it.

Articles on Diseases of Fish

Article 1 – General Overview – Part 1

Article 2 – General Overview – Part 2

Article 3 – General Overview – Part 3

Article 4 – Freshwater White Spot – includes overview of diagnostics applicable to both saltwater and freshwater.

Article 5 – Chilodonnella (FW) & Cryptocaryon irritans – Marine White Spot

Article 6 – Trichodonella (FW) & Uronema (SW)

Article 7 – Gyrodactylus (FW) &  Brookynella (SW)

Article 8 – Oodinium -  Freshwater & Saltwater

Articles on Diseases in Nature

Article 9 – Shrimp disease Asia

Article 10 – Mycobacteria TB

Article 11 – Columnaris

Article 12 – EAFP conference Heriot

Article 13 – Vibrio

Article 14 – Tetrahymena and buying better fish

Article 15 – Common Q&A’s

Articles may not be reproduced without asking the author’s permission, which will not be withheld unreasonably.

Tim Hayes

Midland Reefs

©2011

Dr. John Shawn Prescott

©2011

The CO2 Calcium Reactor.

In the third part of my series on methods of maintaining levels of calcium and carbonates in the reef aquarium I’m going to take a look at CO2 calcium reactors. These are, perhaps, the most expensive pieces of equipment commonly purchased to maintain calcium and carbonates, but they can be the cheapest to run. Why is this such an expensive route to take? Well, when you first go this route, you find you actually need to buy two items of equipment, not just one, which of course pushes the price up. For a calcium reactor to work you also have to buy a CO2 bottle plus control gear at the same time as buying the actual reactor.

How does it work?

A CO2 reactor is a container used to hold calcareous media through which tank water, mixed with CO2 gas, is passed. By adding CO2 gas to the tank water, the pH value of the water is reduced, when the pH drops into the range of 6 to 6.5 pH it’s then acidic enough to dissolve the calcareous media, The water that leaves the reactor is high in calcium and carbonates which are now available for corals to use in the process of calcification – skeleton building. What’s more, the calcium and carbonates made available by this method are in the correct balance that’s so important for the reef aquarium.

How do you set up a CO2 calcium reactor?

It’s common practise to run a calcium reactor of this type by either tee-ing off from existing pipe work or by using a small, dedicated pump for the purpose. The flow of water through one of these reactors is generally quite low, as you’ll see when I describe how they are controlled.

With this type of reactor you can control the output by both adjusting the rate at which CO2 is fed to the reactor and by regulating the flow of water through the reactor.

To help control the rate at which the gas is fed into the reactor a device called a bubble counter is employed. This is simplicity itself, a small transparent container that is part filled with water and positioned so that the gas flows through it on the way into the reactor. You can then observe bubbles of gas moving through the water and, as the name suggests you count the bubbles as a way of quantifying the delivery.

The amount of water passing through the reactor is controlled by restricting the flow before it reaches the reactor and, again, this flow is quantified by observation, only this time you measure the flow by counting the drops of water returning to the aquarium over a given period of time. So, at the simplest level, you can control the reactor by a combination of bubbles of CO2 per second and drops of water per second.

Now, just because this is such a simple method it certainly doesn’t mean that it’s an inferior one; in fact, although it may seem a bit basic, it has the virtue of simplicity. You can see at a glance that water and gas are feeding through the system, and a quick bit of mental arithmetic will confirm that the flow rates are correct. Compare that to the more high-tech approach, where it’s impossible to tell just by looking if a pH probe is running accurately, or if an electrically operated solenoid valve is open or closed.

The production of the reactor can be evaluated simply by testing the water being fed back to the tank. Measure the alkalinity (in this case the quantity of bicarbonates and carbonates not a measure of acidity) of this water; the value here will be most usually be read in either meq/l or dKH (1.0 meq/l = 2.8 dKH), the higher the reading, the higher the reactor’s output. Although this can be useful, remember it’s the levels of calcium and carbonates in the aquarium that really matter.

A more technical solution to controlling the output of this type of reactor is to add a probe to measure the pH level within the reactor, a solenoid to turn the flow of CO2 on and off, and a controller that can be set to operate the solenoid at a given level of pH. As the way this reactor operates is by acidifying the water we can use the resulting pH reading as a guide to the correct operating of the reactor. Generally we’d be looking at a pH of somewhere in the region of 6.0 to 6.5, although the optimum level will be dependent upon the media being used in the reactor. Different types and grades of media will differ in the ph required to bring about the release of calcium and carbonates, and ideally we would like to use the media that works for us at the highest pH level we can manage. The reason for this? Well, one of the downsides of this type of calcium reactor is that lowering of the tank’s pH can occur.

Note: in addition to type and grade of media influencing the pH level required to operate the reactor, poor quality media can also release phosphate into your reef system. I recommend checking the amount of phosphate your chosen media releases by using an appropriate test kit.

Correcting low pH.

The water returned to the tank is high in calcium and carbonates, but has a low pH in the range of 6.0 to 6.5. Over time this will tend to depress the overall tank pH. To a certain extent, a lower pH isn’t much of a problem, as corals will still calcify down to 7.8 pH. But what may happen is that the lower pH will be responsible for helping to fuel outbreaks of undesirable algal growth.

There are a number of ways of dealing with this lowering of pH. A reef with high levels of surface agitation or excellent gas exchange may experience no problems whatsoever. So, one of the simplest methods is to just use increase gas exchange within the aquarium – this will gas off excess CO2, enabling a more natural pH to be maintained, say around 8.2. This can be done by increasing flow in the tank, or by increasing the rate water is returned to the sump. Simply adding an air pump to aerate water in the sump can also be an effective measure.

A more advanced method is to add a second reactor chamber containing more calcareous media, the theory here is that the acidic water will release more calcium and carbonates from this extra media, and that this, in turn, will use up the excess acidity. This reactor can also contain phosphate remover to negate any phosphate released from the media.

By running kalkwasser in conjunction with a CO2 reactor, you can take advantage of its high alkalinity to counterbalance the acidity produced through the use of CO2.

Safety.

There are a few potential dangers inherent to the CO2 reactor. Some of these are dangers to the aquarist and his family; others are to the reef tank.

The CO2 bottle containing the gas is pressurised to 50 bar or 725 pounds per square inch (PSI). This is a potential bomb or, more accurately, rocket. The greatest danger lies at the point where the valve or regulator attaches to the bottle – if the bottle falls over, damaging this region or possibly breaking off the regulator, the sudden escape of gas under pressure can propel the gas bottle in the same way as a rocket engine. This is a reaction that won’t stop until the gas is exhausted. A pressurized gas cylinder can, with the valve broken off, become a rocket attaining a speed of thirty-five miles per hour in around a tenth of a second. So, the number one tip here is to restrain the bottle to prevent it from being able to move. In the case of smaller bottles, many manufacturers supply simple brackets that hold the bottle securely in place. For larger bottles you may need to secure the bottle to a wall, or the side of your cabinet, with a chain of the sort used in industry.

CO2 bottles should be stored upright and away from heat. If a bottle overheats, the gas pressure within the bottle can rise to a point where the safety valve will release the contents of the bottle to the atmosphere. This can be both distressing and dangerous, particularly in an enclosed space, for example while transporting a gas bottle in your car on a hot day.

The danger to your reef is that if your system is incorrectly set-up or if “little fingers” start fiddling with the settings, it’s quite possible to depress the pH level of your reef to dangerous levels. So, firstly ensure that you set your reactor up properly, and that when first setting it up, you check and recheck the performance of your new acquisition until you’re happy that it is set correctly. As far as outside interference goes, well, there’s education, or perhaps more reliably, placing the bottle in a location where the settings can’t be changed by a third party. Some manufacturers have safety measures of one sort of another to prevent inadvertent or casual adjustments.

If your control mechanisms fail, you could end up with the entire contents of your gas cylinder being dumped into your aquarium, resulting in a devastating lowering of pH with the potential to wipe out your system.

Pros and cons.

Cons.

• Initial expense.
• Tendency to lower the pH of the system.
• The possibility of phosphate being released from the calcareous media.

Pros.

• Once you’ve got over the initial cost of this system you’ll find it very economical to run.
• For larger tanks, and ones with a high demand owing to a high population of stony corals, this can be the only economical of supplying the necessary amount of calcium and carbonates.
• Once set up, apart from a daily glance at the bubble counter and the drip rate, there’s nothing else to do except enjoy watching your corals grow.
• Gas or media replacement is only needed infrequently, giving you more time to spend on other tasks.
• Apart from carrying out a bit of appropriate equipment maintenance when you replace the media or gas bottle, this method requires very little input on behalf of the aquarist.

(I think that by this point you’ll have got the message that, if set up correctly, it’s a doddle, requiring little or no attention except for keeping an eye on bubble rate and drip rate. All in all a very low maintenance, non- time consuming method of keeping calcium and carbonates at the correct levels and balance.)

Hints ‘n’ Tips.

• When you’re preparing to fit a new or refilled bottle, it’s worth “cracking” the bottle. This term refers to the practice of opening the valve of the bottle a little way, then closing it again prior to fitting the regulator. This results in a loud crack, and the resultant displacement of any muck from the valve that might other wise block up the regulator, preventing the flow of gas.
• When the gas in your bottle is nearly used up you’ll find it becomes empty very quickly. Don’t get caught out.
• As most CO2 kits come with a small capacity bottle, I’d recommend purchasing a more realistically sized bottle, say one of two litre capacity. When the larger bottle is exhausted, use the small bottle to run your tank while you wait for the empty bottle to be refilled.
• If using an air pump to help bubble off excess CO2, try using a rigid pipe in place of an air stone.
• Don’t be tempted to cut costs by using cheaper calcareous media. Poor quality media may have the unwanted side effect of releasing phosphates into your reef.
• If phosphates are released from the media this can be easily remedied by dripping the product water into the aquarium through a quality phosphate remover such as that produced by Reef Scientific.

Conclusions.

The three different ways of maintaining calcium and carbonates that I’ve covered in this series all have their own pros and cons:
If you have a small reef, then you can’t really go wrong using a Balanced Two Part Additive. It also provides a useful supply of calcium and carbonates when correcting an imbalance in the aquarium.
Kalkwasser has unique characteristics making it useful as an additional supplement. It is used in conjunction with a protein skimmer as a means of reducing phosphate levels, and, given the high pH value, its use in helping to balance the potential acidification of the CO2 calcium reactor.
The CO2 calcium reactor is the most economical way of replacing calcium and carbonates in larger aquaria, or ones exhibiting a higher than average demand. It’s also the least time consuming method of the three.

From a personal perspective, I’m inclined towards a combination of methods as the need arises. A CO2 calcium reactor plus Kalkwasser, to prevent a tendency toward low levels of pH, makes very good sense. Add in the use of a Balanced Two Part Additive, but at a lower level than is needed to maintain correct levels on its own. You may find you can benefit from the pros of each of the methods, at the same time as cancelling out the cons.

Tim Hayes
Midland Reefs
©2009

Kalkwasser aka Calcium Hydroxide.

Following on from the article about using liquid supplements to support the calcium and carbonate requirements of your corals, in this article I’m going to look at the use of Calcium Hydroxide in the reef aquarium.

Kalkwasser is a saturated solution of calcium hydroxide in water that’s used to help replenish the calcium ions required by corals to grow. The name Kalkwasser (German for lime water) reflects this method’s origin in Germany, where it was first used by one of the pioneers of the reef aquarium Peter Wilkens. Peter first described the use of Kalkwasser as a way to support the required levels of calcium and to maintain alkalinity in 1973.

The original rationale behind Kalkwasser was that calcium could be made available to the corals at the same time as evaporation losses were being made up. Its use also brings with it a few extra benefits:

It acts in the same manner as a balanced additive; although kalkwasser contains no carbonate component of its own, its addition to the aquarium forms carbonates and bicarbonates due to the combination of the hydroxide ions with CO2 in the water.

Kalkwasser helps to limit inorganic phosphate levels by precipitating phosphate from the water.

The effectiveness of protein skimming is enhanced.

The high pH helps to counteract the natural tendency of a captive reef system to acidify over time.

To sum up, you should enjoy better coral growth when using kalkwasser as you’ll be supplying calcium and carbonates in a balanced manner, while the pH of the reef will be kept at a level better suited to calcification, and phosphate (which can inhibit calcification) will be kept low.

Health warning!

Calcium Hydroxide is a dry, fine powder that needs to be treated with respect. It is potentially dangerous to you, your family, and your livestock, so remember to take precautions!
If you were to take a look at a safety data sheet of the type used in industry you’d see some or all of the following information:

DANGER! HARMFUL IF SWALLOWED OR INHALED. CAUSES BURNS TO SKIN AND EYES. CAUSES SEVERE IRRITATION TO RESPIRATORY TRACT.

• Personal protection: Wear suitable protective clothing, goggles, dust mask, and chemical resistant gloves.

Potential Health Effects

• Inhalation:  Causes irritation to the respiratory tract. Symptoms may include coughing, shortness of breath. Can cause chemical bronchitis.
• Ingestion: Gastric irritant. Ingestion may be followed by severe pain, vomiting, diarrhoea, and collapse. If death does not occur in 24 hours, oesophageal perforation may occur, as evidenced by fall in blood pressure and severe pain. A narrowing of the oesophagus may occur weeks, months, or years after ingestion, making swallowing difficult.
• Skin Contact: Corrosive. May cause severe burns and blistering, depending on duration of contact.
• Eye Contact: Corrosive. May produce severe irritation and pain. May induce ulcerations of the corneal epithelium. Can cause blindness.
• Chronic Exposure: Prolonged or repeated skin contact may produce severe irritation or dermatitis.
• Aggravation of Pre-existing Conditions:  Persons with pre-existing skin problems or impaired respiratory function may be more susceptible to the effects of this substance.

First Aid Measures

• Inhalation: Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Call a physician immediately.
• Ingestion: DO NOT INDUCE VOMITING. Give large quantities of water. Never give anything by mouth to an unconscious person. Call a physician immediately.
• Skin Contact: In case of contact, wipe off excess material from skin then immediately flush skin with plenty of water for at least 15 minutes. Remove contaminated clothing and shoes. Wash clothing before reuse. Call a physician immediately.
• Eye Contact: Immediately flush eyes with gentle but large stream of water for at least 15 minutes, lifting lower and upper eyelids occasionally. Call a physician immediately.

OK, I’m not really trying to scare you with all this information, I just want to emphasise the importance of careful handling and illustrate why its important to keep children and pets out of the way when making up kalkwasser or recharging a kalk reactor.

Note: Too much kalkwasser, or too much added too quickly, can raise pH to unacceptably high levels causing pH shock resulting in the death of livestock.

Note: Never allow undissolved calcium hydroxide to settle out on corals as, at the very least, this will lead to localised tissue loss.

Description.

Calcium Hydroxide is strongly alkaline, when freshly made up into a saturated solution it has a pH of 12.4 with a calcium concentration of 900 mg/l. Over time, just a matter of days, this solution will react with the CO2 in the atmosphere, as it does the PH will start to drop and as the pH drops so will the amount of available calcium. The reduction in available calcium is very abrupt, by the time the pH has dropped to 12.0 calcium will be just below 200 mg/l, and by the time the pH reaches 10.0 calcium level will have plummeted to around 5 mg/l, rendering it no use whatsoever. When kalkwasser reacts with the CO2 from the atmosphere calcium carbonate is formed. Now we actually want calcium carbonate to be formed by the corals themselves through the process of calcification by which they build their skeletons, we don’t want to be just introducing calcium carbonate into the aquarium as in this form the calcium and carbon aren’t available for coral growth. This explains why you should never attempt to mix calcium hydroxide using an air stone, which would add CO2, making your calcium additive useless!

Paradoxically, the formation of calcium carbonate through contact with the atmosphere can be used to our advantage. When kalkwasser is made up for either drip dosing or is used in most kalkwasser reactors you’ll see that a milky film will develop on the surface of the solution. This film is calcium carbonate, showing where the kalkwasser has reacted with CO2. Now, as long as we don’t disturb this film and only take kalkwasser from below it, the film is acting as a barrier to the additional uptake of CO2 and is actually protecting the kalkwasser from further deterioration.

Note: Remember to always using purified water i.e. RO water when mixing kalkwasser, especially when used for evaporation replacement.

Dosing Methods.

Timing.

Different authorities offer differing advice about the timing of Kalkwasser additions. Many recommend dosing solely at night when the pH of the aquarium drops to its lowest level as the high alkalinity of this additive helps counteract this phenomenon; others recommend dosing at regular intervals throughout the day and night to limit spikes in both pH and calcium, keeping these levels as constant as possible.

Reactors.

Kalkwasser reactors are usually used as part of an automatic evaporation top up system. With an auto top up system a water level sensor or float switch in the sump (or in the aquarium if no sump is present) will activate a top up pump in response to falling water level due to evaporation, which will then pump water from a reservoir into a high flow area of the sump (or aquarium), when the sensor is back to its normal level the pump switches off. When a kalkwasser reactor is included in this system it’s placed between the water reservoir and the reef, water will then replenish the reactor at the same time as calcium rich water is added to the aquarium.

Reactors employ a device to stir the calcium hydroxide solution; depending on manufacturer this can be a stirring rod operated by a motor in the lid of the reactor, a magnetic stirrer operated by a motor below the reactor or a pump (depending on design centrifugal pump operated reactors can be a poor choice).
With a kalkwasser stirrer continually mixing the calcium hydroxide and RO water being introduced in response to evaporation losses, there is no need to make up a solution and let it clear before use. Monitor the pH of the solution being added to the reef, when it drops below 12 add another dose of calcium hydroxide to the reactor. Every month or two when the pH has fallen below 12 strip out and clean the reactor, setting it up anew.

Drip Dosing.

This is the original method of dosing kalkwasser. Essentially a kalkwasser solution is made up, then allowed to drip into the reef over a period of time. Its usual to employ gravity for this form of dosing although you can also use a peristaltic pump fro the job as long as you can control the rate of delivery. A simple method is to employ a siphon from a reservoir mounted higher than the point of introduction (either in the tank or the sump), which should be a high flow area to promote rapid mixing of the solution with the aquarium water. Use airline tubing and then control the drip rate with an external clamp.

Note: If you use a tap to control the drip rate you’ll find it’ll clog more readily and will need more frequent cleaning.

I’d suggest that the first time you use this method  you do so when you have a little time on your hands so you can monitor the pH of your reef as you adjust the drip rate. It’s difficult for me to prescribe a drip rate of “x” drops per minute as all reefs are different and this rate would be very much down to your pre-existing pH. As a pointer, calculate how much water is lost through evaporation each day, then set yourself a drip rate that’ll replace that volume over twenty four hours.

Mixing the Kalkwasser.

Calcium Hydroxide doesn’t readily dissolve, it’s one of those unusual compounds that actually dissolves better in cold water than hot so always use cold RO for your make up water. Add about a quarter teaspoon / 1.25 ml by volume of Calcium Hydroxide per litre of water and stir vigorously. Leave the solution to clear then decant the clear saturated liquid into your dosing reservoir. (There will be a certain amount of undissolved calcium hydroxide leftover in your mixing container that can be used to make up a further weaker solution of Kalkwasser – otherwise safely discard the residue down the drain)

Note: For best results always use freshly made up kalkwasser.

Manual Dosing.

It is possible to dose calcium hydroxide manually in a way that’s both economical and quick. This is a method I’ve used successfully myself and was first described to me by Anthony Calfo. To succeed with this method you need an electronic pH meter to help you fine tune the dosage and to ensure that the pH doesn’t rise to potentially dangerous levels.

Take a small container, I use a one litre jug, and add about 200ml of cold RO water. Check the pH of your reef. Add no more than a quarter teaspoon / 1.25 ml by volume of Calcium Hydroxide to the jug and stir vigorously, pour this into an area of high water movement where it will readily mix with the tank water then use your pH meter to monitor the rise in pH. You can safely allow yourself a maximum rise in pH of up to two points i.e. 8.2 rising to 8.3 or 8.4 is fine, if it goes over 8.4 reduce the dosage the next time, if there’s no significant increase in pH then the next time you dose, add slightly more calcium hydroxide.

The recommended dosage here is for a 200 litre reef, pro rata this dosage according to the size of your aquarium then use the increase in pH as a guide to fine tuning your system’s requirements.

Which is the Best Calcium Hydroxide to Use?

Calcium Hydroxide is available from many aquarium manufacturers and suppliers, usually under a brand name. This is a common chemical with uses outside of the aquarium hobby; as a result it’s available in a number of different grades and purities. Ideally, we want a pure grade, although there are some trace elements which might be useful in the reef tank, magnesium, strontium, etc., there are just as many undesirable ones e.g. phosphate and heavy metals.

So how to choose? Unfortunately, I think all you can do is to try a few different manufacturers offerings and then stick with the one that seems to work for you. Price may be a guide, the purer forms will tend to be more expensive to purchase, cheap low grade products may contain a higher quantity of useless calcium carbonate, but unless you have access to a mass spectroscope it’ll be difficult to quantify!

Whatever product you choose, store it carefully away from children and make sure you reseal the container properly to limit exposure to CO2 from the atmosphere.

Pros and Cons.

As you’ll remember from the previous article, whatever method of supporting calcium and carbonates is used there’s no perfect solution; each method has its own pros and cons.

Kalkwasser pros:

• One of the most cost effective ways of supporting calcium and carbonate levels in a reef.

• Can help deal with the problem of phosphate.

• Improves the effectiveness of protein skimming.

• Counters the decline in pH that can occur over time in the aquarium.

• Cancels out excessive levels of CO2 that may result from the use of a calcium reactor.

• Nothing is added to the aquarium that might accumulate over time to the detriment of the environment.

Kalkwasser cons:

• Limited amount of calcium available making it most suited to calcium level maintenance.

• Unlikely to maintain levels in aquariums with higher rates of calcification.

• With covered aquariums there may not be enough evaporation taking place to allow effective kalkwasser dosing.

• Calcium hydroxide reactors are expensive items of equipment to purchase but the running costs are low.

• A kalkwasser reactor can constitute very real dangers to your reef if something goes wrong resulting in an overdose and a consequential rise in pH.

• Calcium hydroxide is a very caustic powder that should be handled carefully and kept away from children and pets.

Conclusions.

As with the previous article, I’m left to conclude that ultimately the best solution to calcium and carbonate supplementation lies with the combination of more than one method, this will allow you to get the best from each, while cancelling out the deficiencies presented by any individual method.

Tim Hayes
Midland Reefs
©2009

Keep it Balanced.

One of the most import considerations when it comes to maintaining calcium and carbonate levels in the reef aquarium is, that whatever method is used, it must be a balanced one. Corals need calcium and carbonates to be available in a particular ratio in order to build a healthy calcium carbonate skeleton. If this balance is not maintained the consequences can present themselves as a difficulties in maintaining pH, calcium, and carbonate levels. For a supplementation to be described as balanced it needs to be providing something in the region of 20 ppm calcium along with 2.8 dKH (1meq/l) carbonates.

Many of you of course will be familiar with liquid supplements for calcium dosing but probably think of them as being pretty basic stuff only suitable for beginners. In fact liquid supplements for maintaining calcium and carbonates can be very sophisticated products, superior in some ways to the more technical solution offered by calcium reactors.

Although there are plenty of different supplements for both calcium and carbonates on the market, many of these are unsophisticated products that will replenish calcium or carbonates but with long term use result in ionically unbalanced water. This can be particularly dangerous if water changes aren’t carried out on a regular basis. With no water changes, levels of sodium and chloride from these supplements can build up producing water that’s more like a solution of table salt than seawater!

There are three types of liquid calcium supplements of real interest to us, these are the ionically balanced two part supplements, the Balling Method, and what I would describe as hybrid systems which seem to combine elements of the first two. The theory behind all of these methods is fairly similar as they all aim to add calcium and carbonates in a balanced manner, the differences tend to be in terms of how associated ions, minor and trace elements are included into the dosing regime.

When using any of these systems I’d advise keeping a watch on the salinity of your reef as one side effect of these various methods can be an increase in salinity. With use it will soon be apparent how much the salinity is shifting and you can then work out a simple solution to correcting the problem, for example every so many days or weeks removing a given volume of water from the aquarium and replacing it with fresh RO.

Balling Method

This system of calcium replenishment was originated by Hans-Werner Balling and first published in 1994. Essentially the system consists of dosing calcium chloride and sodium bicarbonate as separate solutions in a strict ratio but as the chloride and sodium ions are not used in the aquarium, a third additive is required to balance out what would otherwise produce an increase in salinity. This third solution added to the aquarium is, in effect, a sodium chloride free sea salt mix that brings with it many minor and trace elements.

Balling Light

A comparatively recent introduction, a kind of ‘lazy reefkeepers’ version of the the Balling Method that dispenses with the use of sodium chloride free sea salt mixture and relies instead on regular water changes to control salinity increases.

See; EcoBalling Method.

Two Part Balanced Ionic Supplements

These two part systems are designed to add calcium and carbonate, along with their associated ions in a manner mimicking the natural ionic ratios of seawater.  The calcium component will include some or all of the following ions (depending on manufacturer): bromide, calcium, cesium, chloride, chromium, cobalt, copper, iron, lithium, magnesium, manganese, nickel, rubidium, strontium, zinc. While the carbonate component will include some or all of the following ions (depending on manufacturer) bicarbonate, borate, carbonate, fluoride, iodide, molybdate, potassium, sodium, selenate, tungstate, vanadate. Overtime you’ll register a slight increase in salinity as, in a sense, it’s almost like dosing with a concentrated sea salt mix.

Hybrid Systems

A number of manufacturers produce what I’d describe as hybrid systems, they’re not Balling Method and neither are they strictly a two part solution.
They tend to consists of three to five parts parts – two of them being a two part calcium/carbonate additive with the additional parts being various trace element mixtures which, like the calcium and carbonate additives, need to be dosed separately.

Better Than a Calcium reactor?

Well yes and no.
Liquid dosing doesn’t introduce any phosphate into your reef system, whereas a calcium reactor, depending on the quality of the media being used, can be the source of unwanted levels of phosphate.
Liquid dosing won’t alter your pH, although it may help support it, however a poorly set up calcium reactor can easily lower the pH of your reef.
Liquid dosing can often be an almost complete source of supply of minor elements and trace elements.
Liquid dosing will contribute far more available calcium than calcium hydroxide (kalkwasser).
For covered aquariums where there’s not enough evaporation to allow kalkwasser dosing or for reef tanks where there’s no sump space to allow for a CO2 reactor, liquid dosing can be the best solution to calcium replenishment.
Knowing the calcium demand of you reef you can easily calculate the required dosage from the manufacturers product information; usually the manufacturer will tell you how many mg/l calcium is provide for a give dose. Getting the dosage right with a calcium reactor can involve making a lot of adjustments to flow rates at the same time as performing a lot of calcium and carbonate testing before determining the correct settings for your reef.
Manual liquid dosing can be a more economical solution for smaller reefs, or reefs with a lower calcium demand where a calcium reactor might seem to represent expensive overkill. As the size of the reef system or the calcium demand of the corals increases the cost of the supplements used for liquid dosing can become high compared to the running costs of a calcium reactor (replacement media and CO2).
Calcium reactors are expensive items of equipment to purchase but the running costs are low.
Both forms of calcium reactor, kalkwasser reactor and CO2 reactor, can constitute very real dangers to your reef if they go wrong and are also potentially dangerous to you the aquarist. Calcium hydroxide is a very caustic powder that should be handled carefully and kept away from children and pets. Carbon Dioxide (CO2) is kept in pressurised cylinders which if mishandled may explode.

Ultimately the answer may lay with combining the two methods to get the best from each.

How to dose manually.

Some manufacturers may suggest leaving a minimum time between dosing the separate parts (say 20 minutes apart), whereas others may just say to dose the separate parts into a high flow area of the aquarium.
Always follow the manufacturers guidelines. Though, having said that, when instructions are given for weekly dosing there are benefits to be had if you pro rata the recommendation to a daily dose.

Automatic dosing.

Automatic dosing involves the additional cost of purchasing dosing pumps but brings with it a number of advantages.
Once your dosing regime is set up or programmed you can forget about the hassles of having to remember when to dose and with how much. Maintenance becomes a matter of replenishing each part of your supplement as they become exhausted. Depending on the demand of your reef and the volume of the containers holding the individual solutions you can go some time with out having to pay attention to calcium dosing. Nevertheless, I’d recommend checking calcium and carbonate levels each time you restock. There are two reasons for periodically measuring calcium and carbonate levels. Firstly, to ensure you’ve accurately calculated out the correct dosage and that the pumps are operating as desired. Secondly, now you’re making appropriate quantities of calcium and carbonates available at a near constant level, you’ll most likely find that as your corals benefit from this, that they’ll grow and hence the demand will increase.

Liquid supplements can be easily added to the aquarium automatically by using dosing pumps. This is usually done by the use of peristaltic pumps.
These pumps consist of a casing, a rotor, and a length of special hose. The rotor has two or more short arms ending in rollers, as it rotates these rollers squeeze the hose against the housing in turn, as each roller squeezes the hose it pushes a small volume of liquid along the length of the hose and through the pump. More expensive pumps can be programmable, while cheaper, non-programmable pumps can be controlled by using an aquarium computer system. Most domestic timers will be unsuitable for this application unless they’re capable of switching dosing pumps on and off for timed periods of a minute or less.
A separate container is required for each different component being dosed; the pump then draws the solution from the container, through the pump, and feeds it into the aquarium. This is all done through 6mm diameter airline tubing and it’s usual to employ an airline check valve somewhere along the line to ensure efficient delivery. Depending on the make of your programmable pump you can alter how may times a day it’ll dose and how long it’ll dose for.  Most of these pumps have a fixed dosing rate so it’s the length of time the pump is working throughout the day that’ll control the volume of liquid dosed. If the pump has a dosing rate of 3l/hr and we want to add 50ml a day that represents a running time of only one minute, so it may well pay to dilute the liquid with RO water to allow repeated dosing throughout the day.
The various feeds from the doser should be delivered into a high flow area and, if the pumping system is going to deliver more than one component at a time, should be spaced apart accordingly. Perhaps a minimum spacing of 10 cm between dosing locations.

Hints and Tips.

Most importantly, remember to never mix the calcium and carbonate components of any of these multi-part liquid supplements together in a container prior to dosing. You’ll just end up with calcium carbonate in a form that’s not accessible to your corals.
If it appears to start “snowing” in the tank after the addition of the calcium and carbonate liquids this means calcium carbonate is being precipitated out of solution. You need to either dose further apart or into a higher flow area of the tank. It may also be worth double-checking your calcium levels to make sure you’re not in a state of calcium supersaturation.
Before starting to dose with a balanced liquid supplement it’s advisable to ensure that your calcium and carbonate levels are at, or near, to the correct levels for a reef tank. Somewhere in the range of say, 380 – 440 ppm calcium 7 – 11 dKH.
If you’re dosing automatically, using peristaltic pumps, then I’d recommend that you break up the daily dosage into a number of smaller doses to be administered throughout the day. This way you can minimise fluctuations in the calcium levels and offer a steadier environment, reflecting the constant levels found on the reef in the wild.

Correcting Calcium and Carbonate Levels.

Your calcium and carbonate levels can be out of balance in a number of different ways, each requiring a slightly different method of correction.

1. Calcium and carbonates too high: – discontinue all forms of supplementation and wait for the levels to naturally decrease. Monitor regularly.
2. Calcium and carbonates too low: – add balance liquid supplements at a slightly higher dosage than recommended. Monitor until acceptable levels are reached and then cut back on dosage until maintenance of required levels is achieved.
3. Calcium too high, carbonates too low: – add carbonate component only. Monitor both parameters until back in target range.
4. Calcium too low, carbonates too high: – add calcium component only. Monitor both parameters until back in target range.
5. Calcium at target level, carbonates too low: – add calcium component at lower dosage, say 50% and add carbonate component at double dosage (don’t exceed manufacturers’ recommended maximum dose). Monitor both parameters until back in target range.
6. Calcium too low, carbonates at target level: – add carbonate component at lower dosage, say 50% and add calcium component at double dosage (don’t exceed manufacturers’ recommended maximum dose). Monitor both parameters until back in target range.

How to Calculate Dosage for Automatic Dosing.

If the peristaltic pump you’re using has a typical dosing rate of 3l/hr that equates to 3000ml/hr or 50ml/min. To find how long you’d need to run this pump to dose a given quantity, divide the required dose in ml by the dosing rate.
Example 1: if you want to add 50ml a day, divide 50 by 50, this gives you a figure of 1 representing a running time of one minute.
Example 2:  if you want to add 25ml a day, divide 25 by 50, this gives you a figure of 0.5 representing a running time of half a minute or 30seconds.
As you can see we are dealing with small dosages and short time periods, so it can pay to dilute the liquid with RO water to allow repeated dosing throughout the day. Take any dilution into account when calculating out your daily dosage.
Example 3: if you take the dosage from example I above and dilute it 1:1 (50ml RO + 50ml supplement) you’d then need to dose 100ml per day, doubling the pump run time to 2 minutes to deliver the required amount of supplement. This extended running time can then be spread over the course of the day by breaking the dosing down to 1 minute twice a day, 30 seconds four times a day, or 15 seconds eight times a day.
Example 4: example 2 above would really benefit from dilution. By diluting 3:1 (75ml RO + 25ml supplement) you could then dose the same number of times as in example 3.

Tim Hayes
Midland Reefs
©2009 – 2011

MarinePure (previously known as ReefresH2O) – The Natural Choice for Fish Hobbyists.

Here are a few of the testimonials we’ve been receiving about MarinePure media. The first couple are from the US where this media has been around for a while longer than in the UK and EU.

“I currently maintain five 55-gallon tanks of Hawaiian fish, and in some of them MarinePure is the only method of filtration I use,” said John Dawe, fish hobbyist and past president of both the Marinelife Aquarium Society of Michigan (MASM) and Midwest Marine Conference, as well as a MarinePure customer for close to 10 years.

“MarinePure is exceptionally reliable, and so convenient to use as an almost instant biofiltration system.  I can literally take a conditioned piece from an existing tank and put it directly into a new tank of quarantined fish, or get a new piece of media ready in just a couple of days by seasoning it in an existing tank,” Dawe explained.  “I wouldn’t use any other biofiltration product.”

“As a long-time hobbyist who has also been in the coral propagation business, effective and reliable media for both filtration and coral growth is important from many aspects,” said Rick Smith, aquatic enthusiast and former fish and coral frag wholesaler.  “MarinePure is the closest product available to reef rock, offering exceptionally high porosity and making it much easier to bore propagation holes than when using concrete-based media.  Offering a neutral substrate with an ability to rapidly absorb up to 30 percent of their weight in micronutrient-rich salt water, MarinePure coral frag plugs promote instant coral adhesion and long-term, healthy growth.”“I’ve been using this product line for about a decade now, and currently maintain a 92-gallon reef tank that exclusively employs MarinePure biofiltration media.  With no need for water changes in more than three years, the tank is full of healthy, thriving corals thanks to MarinePure.”

In the short time that MarinePure products have been available in the UK they’ve proved an unqualified success in the shops where they’ve been tried out, particularly in the marine sector. Retailers using MarinePure products in their shop systems report unprecedented low nitrate levels.

Richard Sendel, owner of Tropical Paradise, Eastleigh, near Southampton placed four MarinePure Blocks in the sump of his 4,500 litre shop fish system which at the time was running at 100 ppm Nitrate, mainly because Richard makes sure his fishes get properly fed 3 times a day. Now, after 10 weeks, Richard is reporting an unprecedented Nitrate level of 2 ppm!

Steve Unwin of Mastin Moor Aquatics is using the Blocks in his fish system; Steve made the additional observation that since installing the blocks in the system, water parameters have become much more stable rather than fluctuating as the fish load varies over the course of the week (as fishes are sold and the system restocked).

Malc, proprietor of Aquatics World, Coventry, using a combination of  Spheres in a large trickle tower along with Blocks in the system, is finding negligible levels of Nitrate in his fish system.

From Switzerland Sascha Sonderegger of Nightsun Aquaristics emailed saying, “I tried a MarinePure block in my live rock tank and the result now is really good. I put it in to the tank on the 17th December with a nitrate around 100mg/l. When I put in new live rock, normally the NO3 will go up a little, this time the NO3 was 25mg/l after 10 days.”
We’ve had plenty more reports from aquarists, both retailers and hobbyists, having great success in reducing and controlling the nitrate levels within their systems. If you’ve got a MarinePure success story that you’d like to share, email me at tim@midlandreefs.co.uk or give me a call on 01543 685599, and I’ll publish your story here.

Tim Hayes
Midland Reefs
©2009 – 11

Water testing in the reef aquarium.

With more than twenty different physical and chemical parameters available for testing in the reef aquarium you may be forgiven if you find the whole subject of water testing a little confusing.

Why do you need to test?

No matter what anyone, no matter how experienced, says, you can’t tell what’s going on in an aquarium just by looking. You need you employ a variety of methods to find out what’s going on in your reef.

Which tests should you carry out?

Broadly speaking you can divide the available tests into three categories: the every day parameters that need to be adhered to, parameters you may need to examine in the case of a problem, and parameters that could perhaps be described as aspirational, ones that might be looked at when trying to optimise an already successful reef.

The essential parameters that need to be monitored in an established reef are: Temperature, Salinity, pH, Calcium and Carbonates, Nitrate, and Phosphate.
With newly set up reefs you’ll additionally need to pay attention to Ammonia and Nitrite and, although calcium and carbonates are of less importance until corals are introduced, proliferation of coralline or calcareous algae can make significant demands of these two parameters.

How do you test?

Depending on parameter we can choose from chemical based tests, electrical probes, photoelectrical sensors, optical instruments, traditional thermometers, and hydrometers. Chemical tests tend to be used for chemical parameters; physical parameters may be measured by a variety of other means.

What can’t we test for?

Given the budget, or access to an extremely well equipped laboratory, there’s not a lot that can’t be measured. But for the average reefkeeper (plus the majority of public aquariums) there’re plenty of things that can’t be quantified, for example the majority of the seventy-odd trace elements that are found in saltwater cannot be readily measured and, even if they could, there may be little merit as these elements, by definition, are available in trace or minute amounts. Their concentrations will be maintained by a combination of regular water changes and the food introduced into the aquarium. Indeed, given the speculation about the accumulation of trace elements in the reef aquarium, the value of water changes is that they can also help dilute any such accumulation.

The more important factors that we can’t test for are biological or biological in origin.
We can’t test for chemicals released into the water as a part of the non-stop chemical war being waged in our reefs by corals and other invertebrates.
We can’t test for the biological oxygen demand (BOD) of our reefs outside of the laboratory. This is the total oxygen demand of all the creatures present in our reefs.

At what levels should the various parameters be maintained?

This is a tricky one. You can aim to replicate natural seawater levels or you can opt for levels that have evolved over the lifetime of the hobby. In reference books you’ll often find discrepancies regarding natural sea water parameters, although the sea can largely be considered stable there are variations. Variations in salinity, temperature, and calcium are widespread, changing with depth, season, atmospheric pressure, and proximity to land. Locally these can change over the course of the year. We are primarily concerned with seawater from tropical latitudes in the vicinity of coral reefs so the figures I’ve quoted reflect this. See: Reef Ramblings – Recommended Reef Tank Parameters.

Temperature.

Measured by traditional thermometer, stick-on external thermometer, or electronic probe.

A reef needs to be maintained at a stable temperature within a fairly narrow range. Water temperature in a reef tends to edge towards the high end owing to the amount of lighting used and, in recent years, there has been a tendency towards a higher than reef safe ambient temperature for a few weeks of the year during the summer months.
Generally reef aquaria should be maintained somewhere between a minimum of 21˚C and a maximum of around 28˚C. For most captive reefs a temperature in the region of 24 – 25˚C, plus or minus one degree, will work well.
Note: some aquarium writers, myself included, advocate slightly higher, more natural temperatures in line with actual reef temperatures (up to a maximum of 32˚C). Higher temperatures result in lower levels of oxygen saturation and increased metabolic rates, factors that need to be taken into account if you decide to go this route.

Dissolved oxygen.

Measured using chemical based test kit or electronic probe.

This is affected by temperature, flow rate, total animal load, and surface agitation. This is an extremely important parameter that’s rarely measured. In practise, a well-designed reef featuring good gas exchange through surface agitation, circulation, and aeration, that’s not overstocked, will most likely have adequate levels of dissolved oxygen. Saltwater holds lower levels of oxygen than freshwater and the higher the temperature the less oxygen available.

Salinity.

Modes of testing: Hydrometer. Electronic probe. Optical instrument (Refractometer)

As with temperature, this is another parameter critical to the survival of the animals in the captive reef.
Best tool for the job here is the refractometer as it gives a direct reading of salinity independent of temperature.
Hydrometers do not actually measure salinity they measure density in terms of specific gravity – it is important that if you’re using specific gravity that you always state the temperature of the sample as density varies with temperature.

Conductivity

Another method used to assess salinity. This uses a probe and meter and is more commonly used in aquaculture. Although accurate, may be misleading if water chemistry is awry, as this is actually a measurement of total dissolved solids and may be indicating the presence of ions other than sodium chloride.

pH

Measured using a chemical based test kit or electronic probe.

In simple terms this is a measure of the acidity or alkalinity of a solution. A pH of 7 is considered neutral, a number lower than this tells you a solution is acid, and a number higher tells you a solution is alkaline. The scale used is logarithmic so a pH of 8 is ten times more alkaline than a ph of 7, a pH of 9 one hundred times more alkaline. Electronic testing is far better than chemical test kits owing to the finer resolution offered.
Note: pH fluctuates over the course of twenty four hours in response to biological activity such as respiration and photosynthesis. Generally pH is lowest first thing in the morning before the lights go on, it rises over the course of the day, peaking at lights out in the evening. For this reason, always test at the same time of day so meaningful comparisons can be made.

Carbonates/Alkalinity.

Chemical based test kit. Measured in milliequivalents per litre (meq/L) or degrees hardness (dKH). 1 meq/L = 2.8 dKH.

This is the buffering capacity of seawater, its ability to maintain pH, resisting the trend towards acidification resulting from biological processes such as respiration. As alkalinity is a function of carbonates and bicarbonates, along with a few other compounds, it can also be used to evaluate the availability of carbon that, along with calcium, goes to providing the material for calcification in corals.

Calcium.

Modes of testing: chemical based test kit, electronic probe (accuracy and reliability not yet proven at hobby prices).

Calcium and carbonates should always be considered together. There is little point in testing one without the other and there is no point aiming for some particular value of Calcium without the Carbonates being balanced in the correct proportion required for calcification.

Magnesium.

Chemical based test kit.

Magnesium has an important role to play in the reef aquarium in supporting the buffering system and in its effects on the process of calcification. Magnesium should be about three times the level of Calcium in the reef so, for example, if Calcium were at 400 ppm you’d expect to see Magnesium at around 1200 ppm.

Nitrogen cycle.

Ammonia, Nitrite, Nitrate, and Nitrogen gas.

Monitoring the nitrogen cycle lets you evaluate how efficiently filtration is taking place. Both Ammonia and Nitrite are potentially lethal and should not be present in the aquarium. Once a reef is established there’s little to gain by testing these two parameters unless you are adding additional livestock or live rock, or if you’ve experienced the loss of a fish or other animal where you’ve been unable to recover the body.
In a newly set up reef monitoring Ammonia and Nitrite will allow you to judge when it’s safe to start adding livestock.

Ammonia.

Chemical based test kit.

When raising larval marine animals it can be useful to employ an Ammonia indicator badge, especially as a larval rearing rarely features filtration. Note: Ammonia toxicity increases with pH. It can be a good idea when running larval systems with no filtration to maintain a lower pH to take advantage of this, as toxicity can then be negligible. Don’t try this in a reef!

Nitrite.

Chemical based test kit.

Nitrate.

Chemical based test kit.

A well set up reef should show little if anything in the way of Nitrate. Although not toxic, as with Ammonia and Nitrite, it’s necessary to monitor Nitrate to ensure the level stays low to help prevent algal growth, at the same time if you’re getting a zero measurement, it may well indicate that a small amount of nitrate needs to be added for the well being of your corals.

Phosphate.

Chemical based test kit.

This is one parameter you certainly want to keep under control. In combination with elevated levels of Nitrate, Phosphate acts as fuel for unwanted algal growth. Additionally, raised levels of Phosphate inhibit calcification in stony corals.
When you use a good quality phosphate adsorbtion medium the only way you can tell if its capacity is exhausted is by regular testing for phosphate. If you reach a point where the level of phosphate is no longer being reduced, or, indeed is increasing, then that’s time to replace your phosphate remover with new.

Minor or Trace Elements.

Chemical based test kits.

Although there are test kits available for these, for some parameters the value of testing is questionable. Some test kits may either produce a result that is difficult to quantify or difficult to reproduce.
Testing of these parameters can be considered aspirational, as when you’re trying to fine-tune a reef to perfection (a questionable pastime) or, more usefully if you’re trying to perfect conditions for a particular difficult coral such as Goniopora species. In this example there’s been a certain amount of speculation regarding the importance of iron and Manganese in maintaining these corals.
These parameters may also come under scrutiny in a last ditch effort to sort out a particularly troubled reef when no other obvious causes can be found.

Boron

Boron is another element that contributes to the buffering system in saltwater. Salts that contain higher levels of Borate may give incorrect readings when standard Alkalinity test kits are used.

Iodine.

The jury is still out when it comes to the utility of adding Iodine to the reef aquarium. Some aquarium writers are against its addition, while others are in favour. Toxic if over dosed, it is important for the growth of many species of macro-algae and is found in the tissue of some soft corals. Iodine exists in a number of different forms in saltwater, which may be one reason that testing produces unreliable results.

Iron.

Given the low levels of Iron in seawater the prospect of testing for it in any meaningful way is slim. However iron is important for algae including zooxanthellae, the symbiotic algae associated with photosynthetic corals.

Silicon.

Silicates shouldn’t really be a problem these days. Before we adopted the practise of using RO water to make up fresh saltwater and for evaporation top up, it was quite common for aquaria to suffer a bloom of brown algae (actually diatoms) after every water change.
RO membranes aren’t as efficient at removing silicates as they are at removing some other elements, consequently special, more expensive membranes are available that remove a greater proportion. This may not be a good idea, silicates are required for the healthy growth of sponges and diatoms, as long as they don’t proliferate excessively, are a useful source of nutrition for many reef animals.

Strontium.

Strontium is another element that’s in dispute over its application in the reef aquarium. Anecdotal evidence seems to support the addition of Strontium, yet there’s some evidence that present day corals don’t utilise it in the same way a corals from the geological record, an oft cited source for the chemistry of calcification. Natural seawater levels should be fine but there is a question over the accuracy of test kits available in the hobby.

Copper.

Chemical based test kit.

Copper isn’t generally a test required for the reef aquarium. The reason for this test is to quantify levels of copper when it’s being used as a therapeutic for fish disease. Copper is toxic to marine invertebrates so can’t be used in the reef, if someone sells you some cheap rock to use in your reef that has previously been in a fish only tank, then I’d certainly suggest soaking the rock in for a week or so before testing whether it’s leaching copper from some previous cycle of medication.

Redox.

Electronic probe.

Redox or Oxygen Reduction Potential (ORP) may be monitored for a couple of different reasons. When using Ozone, a redox probe and controller can be used to control the amount of ozone being applied, and prevent dangerous overdosing from occurring.
A more general usage of an ORP monitor is as an indicator of the overall health of a reef system. Observing a downward trend in the reading alerts you to the fact that conditions in your tank are deteriorating.

Dissolved Organics.

Chemical based test kit.

Gives an indication of the degree of pollution resulting from phenols and other organic compounds

Light output.

Monitoring light output tells you when your lamps need replacing. My recommendation would be to record your light output at a fixed distance from the lamp (in the case of metal halide lamps after they’ve been run for around 100 hours) periodically re-check, then when output has reduced by 30% you’ll know it’s time to replace the lamps. When you do replace an aging lamp, always raise the new lamp to a point where you’re getting the same output as the old lamp to avoid photo shock to your corals, and then gradually lower the fixture over a week to ten days until you reach the original position.
As regards the amount of light used, this depends on the corals being kept and on their original depth on the reef.
The most suitable way of measuring light in a reef is to employ a PAR or Quantum meter, this instrument measures photosynthetically available radiation and can be viewed as quantifying the number of actual photons hitting a coral. Forget about Lux or Lumens, these units are biased towards human perception of brightness and are weighted towards certain sections of the spectrum and don’t give an accurate evaluation of light available to drive photosynthesis.

Turbidity.

Turbidity or discoloration of the water can be closely linked to the above notes about photo shock in corals. If your water is discoloured and you respond by adding carbon to clear it you can end up with your corals suffering from photo shock.
This can be evaluated in a number of ways, from the high tech – PAR meter or other photoelectrical sensor, to the low tech – a strip of white plastic part immersed in the water and then visually comparing the difference in colour above and below the water line.

Bacteria.

The measurement of bacteria in the home aquarium is something of a new concept. By using bacteria dip tests in marine aquariums we may be able to learn more about how our reefs are performing by seeing what levels of bacteria are present. Bacteria can have a significant affect on the total BOD and, while many species are benign, others may become pathogenic under certain circumstances. I’ve not yet applied this testing to the reef aquarium but I’m currently looking a bacteria levels in live food cultures and seahorse tanks to see if there is any correlation between the number of Vibrio species present and the incidence of bacterial disease.

Not just the aquarium.

It’s not just the aquarium water you need to test. It makes good sense to look at the water you use for either making up your salt mix for water changes or for evaporation replacement. Testing here serves the purpose of evaluating the efficiency of your Reverse Osmosis (RO) unit or the purity of RO water bought from a shop. Does the membrane need replacing? Are you introducing Nitrate or Phosphate into your aquarium along with your water?
It’s also worth looking at how your salt mix is performing. Is it at the correct salinity? Is there sufficient calcium in the mix? Is it providing a correctly balanced ratio of calcium and carbonates?

Incidentally, regarding RO water, aquarists often query whether RO water is acid – it’s not, it’s neutral, with a pH of 7.0 at 25˚c. The confusion arises from the fact that the pH probes used in the aquarium hobby are incapable of giving an accurate reading when used to measure very pure water.

Afterword.

Whatever method you’re using for testing, try not to get hung up about hitting particular values. All reefs are different and will all display slightly different water chemistry owing to their unique assemblage of animals. Further more take into account the resolution of your testing method; any reading you get will be plus or minus the resolution of the test used.
If your not testing water at the accepted natural seawater level of 35 ppt or at 25˚C your readings will be inaccurate for some of these tests as concentrations will vary with salinity.

Tim Hayes
Midland Reefs
©2006 – 20011

Suggested Reef Aquarium Parameters.

These are intended as a guide for new reefkeepers. Don’t be too pedantic about trying to keep exactly to any particular figure, except where that figure is a zero. Understand that aquarium test kits aren’t spot on accurate but have a resolution of plus or minus X mg/l or ppm, so again don’t worry over much about exact figures, use the results to reassure yourself that you’re within the quoted parameters. Some parameters have more than one measurement listed to take into account differences in how test kits represent the results. There are other parameters of interest in the reef aquarium but the ones listed below are those of greatest importance.

	Range	Target
Specific Gravity	1.022 – 1.028	1.025
Temperature	75º – 82º F	78º F
	24º – 28º C	26º C
pH *	8.1 – 8.5	8.4 daily average
Calcium *	350 – 450 ppm	450 ppm
Alkalinity *	7 – 10 dKH	8 – 10 dKH
	2.5 – 3.5 meq/L	3+ meq/L
Ammonia	0
Nitrite	0
Nitrate – Nitrogen	< 5 ppm
Nitrate ION	0 – 20 ppm
Phosphate	0
Dissolved Oxygen	c. 7 ppm
Redox 325 – 400 mV	c. 350 mV
Magnesium	c. 3 x Ca. level

Notes:

• Salinity. 35 ppt or 1.025 SG @ 25˚C (salinity represented by specific gravity will vary according to temperature). Variation from full strength seawater will give you inaccurate readings on some parameters as ionic strength will be effected.

• pH, Alkalinity, and Calcium, these 3 parameters are interdependent on each other. The relationship between Alkalinity and Calcium should be a balanced ratio supported by appropriate supplementation – these 2 parameters are in a seesaw like balance, as one goes up the other will go down. I intend to add a calculator to the site to make it easier to understand the correct balanced levels for these 2 parameters.

*pH. 8.2–8.5

*Alkalinity (Carbonate hardness). 2.5–3.5 meq/l (7-10 dKH)

*Calcium. 380-450 mg/l

• Magnesium. 1200-1300 ppm. Natural seawater at 35 ppt is around 1285 ppm

• Phosphate. Less than 0.45 ppm (as orthophosphate) Less than 0.15 ppm (as phosphate – phosphorous)

Tim Hayes
Midland Reefs
©2009

In response to a number of queries about low pH in the reef aquarium I’ve prepared this beginner’s or basic article.

First off, do you actually have a problem?

pH fluctuates over the course of twenty four hours in response to biological activity such as respiration and photosynthesis. Generally pH is lowest first thing in the morning before the lights go on, it rises over the course of the day, peaking at lights out in the evening. For this reason, always test at the same time of day so meaningful comparisons can be made.

What should the pH of your reef aquarium be?

A stable pH of between 8.2 and 8.3 is ideal.

What causes low pH?

There are two main causes of low pH in the reef aquarium:

• The breakdown of waste organic material leads to acidification.

• Insufficient water movement can be a cause of low pH readings. If there’s not enough disturbance at the surface of the aquarium CO2 levels can build up in the water, depressing its pH. By increasing surface water movement, the excess CO2 will be gassed off, returning the pH to normal.

Other causes of low pH:

• Additionally, surface bio-films, or cover glasses that fit too tightly with out allowing for ventilation, can be the cause of low pH readings, again because the CO2 present in the water as a result of biological processes isn’t being allowed to escape.

• And watch out for the Christmas/birthday party effect. It’s quite possible for a large gathering of people, in a poorly ventilated room, to contribute to a lowering of pH in your aquarium by putting unusually high levels of CO2 into the room’s atmosphere.

How can you tell if there’s sufficient water movement to facilitate gas exchange?

You can easily test whether low pH is caused by excess CO2. Measure the pH level of your aquarium, making a note of the reading, then immediately take a sample of the water, half a litre to a litre should do. Remove the sample to another room and aerate it for twelve to twenty four hours, then measure the pH of the test sample. If the pH has risen, this shows that excess CO2 has been gassed off in the intervening time, indicating the cause of your tank’s pH problem is an accumulation of CO2.

Does your reef aquarium feature cover glasses or is the top of it enclosed?

The initial problem of utilising a covered design with a reef tank takes us back to the matter of gas exchange. Even if your aquarium has adequate water movement to facilitate gas exchange, the use of a cover is most likely going to lead to a depressed pH. In a reef aquarium pH is critical and should be in the range of 8.2 to 8.5; with a closed tank any carbon dioxide (CO2) gassed off by water movement is going to be held close to the surface by the hood and can be reabsorbed by the water, lowering the pH.  Yes, you can employ fans to ventilate the cabinet but they’re not always sufficient for the job and have the disadvantage that they’re working in a hostile environment, saltwater and humidity, which will lead to a short operational life and hence they’ll need periodic replacement.

Tim Hayes

Midland Reefs

©2009