Reef Ramblings

A short while back during a visit  to one of my retail customers I came across a hobbyist – retailer interaction that got me thinking. A customer had brought back a yellow polyp rock that he’d purchased earlier in the week, as the coral wasn’t doing very well. During the short time that it had been in his tank the number of polyps had significantly reduced, on noticing this and seeing a small snail on the rock he’d decided to return the coral to the retailer for a refund. The culprit, the small snail on the rock, was in fact a Heliacus species gastropod, commonly referred to as a Sundial snail, a known predator of yellow polyps (and other Zoanthids). The customer’s view was that the shop must be at fault for selling him a “faulty” coral and that the shop should have quarantined the coral ensuring it was “safe” before putting it on sale. As I said earlier, this got me thinking… To be specific, thinking about what a hobbyist should expect when purchasing a coral from a shop.

For me, one of the most exciting aspects of this hobby is never knowing what little extras you’re going to get when you buy a new coral or piece of live rock. Hitchhikers are ever present and can bring organisms into your reef that you’d never be able to buy intentionally. Unfortunately a proportion of these unexpected introductions can be classed as pest species. In the wild few, if any, of these species are truly destructive. It’s only within the confines of a captive reef that they can become a real problem.

The Retailer’s Responsibility?

In light of pests such as Tegastes acroporanus, Red Acro Bugs, it makes me wonder what the retailer’s responsibility is to the customer in terms of passing on pests and pathogens? It’s self evident that no one should sell any animal that’s in a poor state of health but where does that leave us when so many undesirable organisms can so easily be passed on to the customer when selling live rock and corals?
Aiptasia and Majano anemones, predatory nudibranchs associated with soft corals, red flatworms, predatory snails (depending on species these may affect many animal, including corals, clams, and sea stars), mantis shrimps, Montipora flatworms, invasive algae species, and more; as this list shows there are plenty of pest species that can cause the hobbyist problems. It’s one thing for knowledgeable aquarists to be confronted with these pests, but for newcomers it can be devastating. The new reef keeper may well not realise there’s anything wrong and may even think they’ve got something really cool growing in their tank. When the realisation that there is a problem hits, it’s the newcomer who’s least able to cope with the situation. Does that mean the retailer should make the effort to ensure livestock goes out pest free? I don’t know the answer to this, but the aquarist who alerted me to the appeareance of Red Acro Bugs in the UK (early 2008) certainly thinks the retailer who sold him infested corals should take some responsibility,  and so does the purchaser of the Yellow Polyp rock mentioned at the start of this article.

Aiptasia are all too often seen in many shops. I’m not going to say that shops should be totally Aiptasia free as I believe that the odd, isolated, specimen is a useful educational aid for new reef keepers, but coral sales tanks should be kept free of Aiptasia and Majano anemones to prevent them being passed on to you, the customer.
(On the subject of Majano anemones: over the last few years I’ve noticed a number of aquarists commenting on how attractive these small anemones are but lamenting, that as a pest, they couldn’t be kept. If you want to keep Majano anemones, well why not? Just do so in a nano reef where they can be easily kept under control.)

It’s impossible to guarantee that any coral or piece of live rock is pest free, to do so the retailer would in effect have to sterilise the item, leaving it devoid of life.
It would make sense to me for the retailer to deal with any obvious problems such as pest anemones, but unfortunately it seems that many retailers don’t have the knowledge to identify other known, but less common, pest species.
In an ideal world retailers would quarantine their corals, only putting them on sale after around, say14 days. This should be sufficient time for any cryptic coral predators, small predatory snails such as Epitonium or Heliacus species (Wentletraps and Sundial snails) predatory nudibranchs and flatworms, to make their presence known through their negative effect on their host corals. The problems such as mantis shrimps or predatory crabs may be accepted as part of the excitement of reef keeping, but should be removed if seen.
But I have to ask the question, “Are you, the hobbyist, prepared to pay the cost of this service?” Many retailers would view coral quarantine as an extra expense – quarantine tanks and observation time – tying up money in the form of stock that can’t be sold. All this in a climate of the consumer wanting to buy corals for the best possible price with little regard to the amount of time and work put into caring for the stock on behalf of the retailer.

Afterword

For some years now I’ve been saying that introducing corals into existing systems without first quarantining them is a very dangerous practice, a point I’m going to continue to make.
A small quarantine tank should be mandatory for reefkeepers, for a newcomer to the hobby it ought to be included in the budget along with the main display system. Perhaps it may not be a necessity for those with smaller displays, say up to around a metre in length, as most people with this size of tank won’t have the investment in corals. Having said that my personal display reef’ is only a metre long and contains corals worth a couple of thousand pounds.
Ultimately, although it would good to be able to rely on your retailer as a source of trouble free organisms, I feel it’s unlikely that this will ever be the case. The only way of preventing problems from being imported into to your reef is for you, the hobbyist, to take responsibility for your own purchases and quarantine them for a period of observation before adding them to your display.

Whereas at one time corals would die before they had the chance to be subject to disease, we can now maintain most corals indefinitely so it’s not surprising to see an increased incidence of pests and pathogens in the hobby. When you further take into account the increased indiscriminate exchange of frags these days, this magnifies the potential for pests and pathogens to be spread throughout the hobby. When a new pest like Red Acro Bugs comes along it’s due to our success in keeping corals, No doubt we’ll encounter further problems in years to come. In the meantime by exhibiting a little patience, along with the minor expenditure of putting together a simple quarantine system, you can give yourself a little peace of mind.

Tim Hayes
Midland Reefs
©2008 – 2009

Copepods for the Reef Aquarium.

There’s currently a lot of interest about copepods for the reef aquarium and as a food for raising larval animals. In this series of articles I’m going to look at what ‘pods are, why they’re important, and suggest some approaches to home cultivation.

What are copepods?

Copepods are small crustaceans found in both marine and freshwater environments.  Around 12,000 species have been described to date. They are very diverse in terms of habitat and behaviour and are also the most numerous multi-celled animal in the seas. Copepods can be free-living, symbiotic, or parasitic (internally or externally) on almost every phylum of animals existing in water. Life cycle can vary from a few weeks up to a year, depending on species.

Marine species are found everywhere in the seas: as pelagic zooplankton in the open ocean from the polar regions to the tropics, and as benthic organisms. Benthic copepods have adapted to live just about anywhere from the sediment layer in the open oceans to extreme environments such as the deepest ocean trenches, the cold polar ice-water interface, and in the region of hot hydrothermal vents.

Copepods in open-ocean planktonic communities can often be the dominant biomass given their abundance, size, and high lipid content (up to 70% their body weight).

Adult copepods are usually around 1-2 mm in length, but some species may be as short as 0.2 mm whilst others may be as long as 10 mm. Ecologically they are important links in the food chain linking microscopic algal cells to juvenile fish to whales. Copepods have the potential to act as control mechanisms for malaria by consuming mosquito larvae, but they can also act as intermediate hosts of a number human and animal parasites. Branchiura (commonly referred to as sea lice) are also included with the Copepoda, since many copepod researchers also study these parasites of fish.

Kingdom Animalia, Phylum Crustacea, Class Copepoda,
Copepoda consists of 10 Orders:

1. Calanoida
2. Cyclopoida
3. Gelyelloida
4. Harpacticoida
5. Misophrioida
6. Monstrilloida
7. Mormonilloida
8. Platycopioida
9. Poecilostomatoida
10. Siphonostomatoida

The copepods that we’re primarily interested in belong to the orders:

• Calanoida
• Cyclopoida
• Harpacticoida

Why Copepods?

Calanoids, cyclopoids and harpacticoids are of particular interest to reefkeepers, since most species of these orders generally form the first link in the aquatic food chain after phytoplankton, for many aquatic organisms from invertebrates, through fishes, to mammals. They are the second largest source of protein in the oceans, second only to krill. They are the natural food of many fish in the oceans, especially during the early stages of life.

Afterword.

See: Nutrition Part 4: Copepods. For a brief look at the species available for reef aquaria along with some notes on cultivation.

Tim Hayes

Midland Reefs

©2009

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