Hey, Nigel — when you say you’re having a problem with slime, do you mean slime algae (i.e., cyanobacteria) or are you talking about a film building up at the surface of the aquarium? Those are two different kinds of problems and I’m not entirely sure which one you’re dealing with…
Assuming that you’re dealing with an outbreak of slime algae (cyanobacteria), the best way to proceed would be to review the usual measures that are most effective in eliminating outbreaks of nuisance algae, and then we can discuss a product that often produces good results when all other measures prove futile in eliminating the slime algae.
Slime algae can be most unsightly but it is not directly harmful to seahorses. It is, however, an indicator of poor water quality since it thrives on excess nutrients in the aquarium (especially phosphates and nitrates), and of course marginal water quality can certainly be detrimental to our seahorses in the long term.
The best way to get rid of nuisance algae for good is to eliminate the excess nutrients that fuel its growth. There are a number of chemical filtration media products that will absorb phosphates from the water; any good LFS that has reef tanks and carries marine fish and invertebrates should have a number of such products from which to choose.
If you use activated carbon in your tank, it’s also very important to make sure that your carbon is phosphate free and that you change it religiously, replacing the old carbon with fresh new carbon every couple of weeks or so. (If you don’t replace the activated carbon regularly, it will begin to leach the wastes and organic compounds it has absorbed back into the aquarium water once it reaches its capacity.) Carbon is activated two ways, either with steam or with phosphoric acid. The type of carbon that is activated with phosphoric acid contains phosphates, which can likewise be leached back into the aquarium water and promote the growth of nuisance algae. So you will want to avoid that type of of activated carbon, particularly when you’re having a problem with hair algae. The carton or box that the activated carbon came in will be clearly labeled that it is "steam activated" or "phosphate free" or something to that effect if it’s a suitable brand for your aquarium. Activated carbon that is low ash and phosphate-free can help control an outbreak of hair algae if it is changed and replaced with fresh carbon diligently; however, activated carbon that is not free of phosphates or that is not changed regularly can actually contribute to a problem with nuisance algae and degrade your water quality.
In and of themselves, nitrates are relatively harmless and midrange levels are nothing to be too alarmed about. Ideally, though, we’d like to keep them under 10 ppm, and if your nitrates are running on the high side (> 20 ppm) and you have a problem with slime algae or hair algae, you need to try to reduce them as much as possible. In case you haven’t already seen it, I am going to provide you with some information on nitrification and denitrification that explains where nitrates come from and then offer you some suggestions on how to reduce them.
The amount of nitrate that accumulates in your aquarium is related to how much nitrification and denitrification your system provides. Nitrification is the process by which aerobic (oxygen loving) nitrifying bacteria break down toxic ammonia to relative harmless nitrate in a series of steps. Nitrification thus ultimately causes nitrate to build up in an aquarium. Denitrification is the process by which anaerobic (oxygen hating) denitrifying bacteria then convert nitrate into completely harmless nitrogen (N2), which eventually leaves the aquarium. Denitrification thus removes nitrate from your system. This entire process is known as the nitrogen cycle.
Cycling your aquarium simply means to build up a healthy population of beneficial bacteria in your tank that can carry out the nitrogen cycle and breakdown your fishes’ waste products. Ammonia (NH3), nitrite (NO2), and nitrate (NO3) are all nitrogenous (nitrogen containing) wastes. All living aquarium animals whether they be fish or invertebrates excrete these wastes, and they are also produced by the decay of protein-containing organic matter (uneaten food, detritus, dead fish or inverts, etc.). The nitrogen cycle breaks down these wastes in a series of steps into nitrogen gas (N2) which leaves the aquarium as bubbles.
The nitrogen cycle begins with ammonia, which is highly poisonous. In the first step of the cycle, Nitrosomonas bacteria reduce ammonia to nitrite, which is also very toxic, but slightly less so. In the second step of the nitrogen cycle, Nitrobacter bacteria convert the nitrite to nitrate, which is relatively harmless but can become harmful when it accumulates in high enough levels. In the third and final step of the cycle, denitrifying bacteria then convert the nitrate into completely harmless N2, which of course bubbles out of the tank as nitrogen gas. In this way, thanks to the nitrogen cycle, dangerous wastes are converted into progressively less harmful compounds and finally removed from the aquarium altogether.
When we set up a new aquarium, and wait for it to cycle, we are simply allowing a big enough population of these different types of bacteria to build up in the biofilter to break down all of the wastes that will be produced when the aquarium is stocked. If we don’t wait long enough for the cycle to complete itself and the biofiltration to become fully established, and hastily add too many specimens to a new aquarium too soon, they will die from ammonia poisoning or nitrite toxicity. This is such a common mistake among us impatient aquarists, that when fish get sick and/or die from ammonia/ntrite poisoning, it is commonly called the "new tank syndrome."
When your aquarium has completely cycled, the ammonia levels will stay at zero because, now that your biofilter is fully established, there is a large enough population of aerobic (oxygen loving) nitrifying Nitrosomonas bacteria to reduce all of the ammonia to nitrite as fast as the ammonia is being produced. The nitrite levels will likewise stay at zero because there is also a large enough population of aerobic (oxygen loving) nitrifying Nitrobacter bacteria to convert all of the nitrite to nitrate as fast as the nitrite is being produced.
The nitrate levels ordinarily continue to build up, however, because there are simply not enough anaerobic (oxygen hating) denitrifying bacteria to convert all of the nitrate that’s being produced into nitrogen (N2). Since nitrates are being produced faster than they can be transformed to nitrogen, the excess nitrates accumulate steadily in your aquarium.
That’s perfectly normal, since the denitrifying bacteria that carry out that final step, the conversion of nitrate (NO3) to nitrogen (N2), are anaerobes that can only exist in the absence of oxygen. For our aquariums to support life, and for the fish and invertebrates to breathe and survive, our tanks must be well aerated and well circulated so that there’s plenty of dissolved oxygen in the water at all times. That means there are normally very few areas in our aquariums where anaerobic denitrifying bacteria can survive, limiting their population accordingly (which is generally good, since some anaerobes produce deadly hydrogen sulfide gas during the decay of organic matter and would poison our tanks if allowed to proliferate).
Consequently, most aquariums lack a sufficient population of anaerobic denitrifying bacteria to complete the nitrogen cycle and convert nitrate to nitrogen as fast as the nitrates are being produced. The only way to keep the nitrates from building up to harmful levels in such setups is with regular water changes and by harvesting Caulerpa or other macroalgae periodically after it has utilized nitrates for growth. Overcrowding, overfeeding, or under filtration exacerbate the problem by resulting in more nitrates being produced and more frequent water changes being required to control the nitrate levels.
Live rock helps because the oxygen-poor interior of the rock allows anaerobic denitrifying bacteria to grow and break down nitrates. A deep live sand bed (DLSB) also helps because anaerobic denitrifying bacteria can flourish and break down nitrates at a certain depth below the sand where oxygenated water no longer penetrates, but a DLSB can sometimes be difficult to set up and manage properly if you’re inexperienced with live sand. Both live rock and deep live sand beds give aquaria denitrification ability — the ability to complete the cycle and convert nitrate to harmless nitrogen. Ordinarily, about 1-2 pounds of live rock per gallon is recommended – that amount of LR will provide your aquarium with all of the biofiltration you need, as well as adequate denitrification ability. You will then keep nitrates at harmless levels by performing regular water changes, harvesting Caulerpa macroalgae periodically, and good aquarium management.
So nitrate is simply the end product of the process of nitrification, formed during the Nitrogen Cycle by the oxidation of nitrite by aerobic bacteria. Nitrates always tend to build up in a system over time, sometimes in sneaky ways you wouldn’t expect. For example, here is an article from Thiel Aqua Tech that discusses some of the hidden ways nitrate can enter your system:
Click here: No nitrate, removal nitrate, denitrating, denitration
One of the sneaky or hidden ways phosphates, nitrates, silicates and other undesirable compounds can enter our aquariums is through the tap water we use for water changes or topping off our tanks. If the water quality in your town is not what it should be, you may want to consider buying reverse osmosis/deinonized water (RO/DI) for your water changes. Most well-stocked pet shops that handle marine fish sell RO/DI water as a service for their customers for between 25 and 50 cents a gallon. If your LFS does not, WalMart sell RO/DI water by the gallon for around 60 cents, and you should be able to find a Wal-Mart nearby.
Natural seawater is another good option for water changes. Like RO/DI water, natural seawater can be purchased at fish stores for around $1.00 a gallon, depending on where you live. It sounds expensive, but when you consider the alternative — paying for artificial salt mix and RO/DI water and mixing your own saltwater — then natural seawater is not a bad bargain at all. It has unsurpassed water quality and seahorses thrive in it.
You should also be aware that freshly mixed saltwater can have residual levels of ammonia, but if you aerate the newly mixed saltwater for 24-48 before you perform the water changes, the ammonia will be dissipated.
Good ways to reduce nitrates in your aquarium include adding more live rock, installing a deep live sand bed (preferably in a sump), installing a protein skimmer on your tank if your not already using one, and growing and harvesting fast-growing macroalgae such as Caulerpa.
Protein skimmers help reduce nitrates by removing dissolved organics from the water before they can enter the nitrogen cycle. The majority of the undesirable metabolites, organic wastes and excess nutrients that accumulate in our aquariums and degrade water quality are "surface-active," meaning they are attracted to and collect near the surface of a gas-liquid interface. Skimmers take advantage of this fact by using a column of very fine air bubbles mixed with aquarium water to trap dissolved organics and remove them from our systems. This air-water mixture is lighter than the surrounding aquarium and rises up the column of the skimmer until the foam eventually spills into a special collection cup atop the skimmer, which can be removed and emptied as needed. Proteins and other organic molecules, waste products, uneaten food and excess nutrients, and a host of other undesirable compounds stick to the surface of the bubbles and are carried away along with the foam and removed from the aquarium. As a result of this process, these purification devices are typically known as foam separators, foam fractionators, air-strippers, or simply protein skimmers.
In my experience, nothing improves water quality like a good protein skimmer. They provides many benefits for a seahorse setup, including efficient nutrient export, reducing the effective bioload, and increasing both the Redox potential and dissolved oxygen levels in the water. They do a tremendous job of removing excess organics from the aquarium, including phenols, albumin, dissolved organic acids, and chromophoric (color causing) compounds. Their ability to remove dissolved wastes BEFORE they have a chance to break down and degrade water quality makes them indispensable for controlling nuisance algae. A good protein skimmer is an invaluable piece of equipment for keeping your nitrates low and your water quality high when feeding a whole herd of these sloppy eaters in a closed-system aquarium.
I also like the use of macroalgae for controlling nitrate and nuisance algae. Macroalgae use nitrate for growth just like plant fertilizer and pruning the macros regularly is a good way to export nitrate from your system. However, if the macros die in your system, they’ll release the nitrate they’ve consumed back into the aquarium. Fast-growing Caulerpa needs to be pruned properly to prevent vegetative events and avoid this from happening, as discussed below:
Macroalgae act as an excellent form of natural filtration, reducing the available levels of phosphates and nitrites/nitrates. Be sure to prune and trim back the fast-growing Caulerpa regularly; when you remove the clippings, you’re exporting phosphates, nitrates and other nutrients from the tank, thereby helping to maintain good water quality, and pruning the runners helps keep it from going sexual.
When pruning or trimming back macroalgae, take care not to actually cut it. Remember, you’re not pruning hedges or trimming trees — the idea is to carefully pull up and remove continuous, unbroken fronds. Simply thin out the colony of excess strands, gently plucking up convenient fronds that can be readily removed intact. A little breakage is fine, but cutting or breaking too many strands will result in leaching undesirable substances into the aquarium water as the Caulerpa lifeblood drains away. Too much cutting or breaking can thus sap the colony’s strength and cause die offs or trigger the dreaded vegetative events that judicious pruning otherwise prevents.
Another product I like for removing excess ammonia, nitrite, and nitrate is the Poly-Filter Pad (by Poly-Bio-Marine) Here is a product review on Poly Filters that touches on some good ways to use them:
Click here: Saltwater Aquariums Product Review – Poly-Bio-Marine Inc. – Poly Filter Pad
Finally, commercially made denitrators (special filters housing a large population of anaerobic denitrifying bacteria) are also available. They do a tremendous job of controlling nitrates but are rather expensive and tend to be high maintenance, often requiring regular "feeding" and carefully controlled flow rates to operate properly.
The hobbyist should also be aware that dead spots and low flow areas, as well as low pH levels, favor the growth of nuisance algae rather than coralline or macroalgae and marine plants. Eliminating dead spots and stabilizing your pH at 8.2-8.4 can therefore help tip the balance back in the favor of macros and coralline algae, and help prevent problems with nuisance algae.
One simple measure that can thus make a big difference is to try positioning one or more small powerheads so that they increase the circulation in the area where the nuisance algae tends to grow. Better water movement and higher oxygen levels will naturally tend to minimize the growth of slime algae and hair algae in these problem areas.
If your pH is running on the low side, that may also be contributing to your problem with nuisance algae. Correcting the pH and maintaining the alkalinity in your aquarium at the proper level will help you get the nuisance algae back under control.
In my experience, the best way to stabilize your pH at the proper level is to gradually adjust it upwards as usual, and then use a dual-phase or 2-part Calcium Buffer System periodically thereafter. This type of buffer has two parts — an alkalinity component and a calcium component — that simultaneously adjust the carbonate hardness of the aquarium as well as the calcium level, which is very beneficial for seahorses
To adjust your pH to the proper range (8.1-8.4) initially, just obtain one of the commercially made products designed to adjust the pH upwards in saltwater aquariums and use it according to the instructions. Such a product should be available from any good LFS that handles marine fishes and invertebrates; they typically include sodium bicarbonate as their primary active ingredient and are often marketed under names such as "pH Up" or something similar. Just be patient when you are adjusting the pH and don’t add too much of the product too soon. Very often your pH won’t budge at all the first several times that you add the product according to directions. That’s perfectly normal, so don’t be discouraged if your pH stays at 7.8 even though you’ve added several doses of the product you obtained to raise the pH. Don’t don’t be tempted to add more of it or to add it more often than specified in the instructions. The product must first overcome the natural buffering ability of the saltwater in your aquarium before I can change the pH level significantly. It’s like performing a titration — typically, you add several doses and your pH doesn’t budge at all, but then the very next dose you add may change the pH dramatically. Since you never know when that critical point will be reached, remain patient and continue to carefully add more of the product as directed until the pH does start to change, and then adjust it to the desired level as gradually as possible.
Once the pH has been adjusted to the proper level of 8.2-8.4, you then add the alkalinity component of the 2-part buffer system. Next you wait a couple of minutes and add the calcium component of the 2-part buffer system. Your pH should remain stable at that pH thereafter and this method also has the added benefit of keeping your calcium level in the proper range as well. For a typical seahorse tank, you can keep it stable at the desired pH by adding more of the 2-part Calcium Buffer System about once every week or two after you perform your usual water changes with the RO-mixed saltwater.
The 2-Part Calcium Buffer System that Marcie and some of our other members report works well with their seahorse tanks is labeled "ESV B-Ionic" on the bottles, but Sea Balance and many of the other brands do much the same thing. The alkalinity component of these two-part buffers maintains the carbonate hardness or KH in the aquarium, whereas the calcium component maintains the calcium levels in the proper range. Any good marine aquarium store will have a suitable product available for this.
You may also find it helpful to test the total alkalinity, carbonate hardness (KH) and calcium levels of the aquarium. Keeping the alkalinity and carbonate hardness at the right level will help you keep the pH in the desired range. A stable KH will prevent rapid declines in alkalinity and subsequent drops in pH. Calcium is a vital element in any marine aquarium, and seahorses in particular benefit from adequate calcium levels because the breeding males need it for the developing young in their brood pouches.
Here is some additional information that should make the relationship between pH, alkalinity, carbonate hardness and calcium a little more clear:
pH: Optimum level = 8.1 – 8.4 (typically fluctuates between 7.9 at night and 8.4 during the day)
The pH is a measurement of the alkalinity or acidity of aquarium water. A pH of 7 is considered to be "neutral," neither acid or alkaline, while pH levels above 7 are considered to be alkaline or "base," and pH levels below 7 are considered to be acidic. Marine aquaria need to maintain alkaline conditions at all times, and low pH (< 7.6) is especially detrimental to seahorses because it is conducive to Gas Bubble Disease. Normal daily fluctuations in pH are to be expected in the aquarium, and are generally gradual enough not to be stressful (Webber, 2004). Maintaining a sump or refugium with a reverse photoperiod to the main tank can eliminate these natural pH cycles. Regular partial water changes are the key to maintaining stable pH. Buffers can also help but the hobbyist should beware that excessive use of pH buffers may increase KH values to dangerously high levels.
Alkalinity: Optimum level = 2.4 milliequivalents per litre (meq/L), which is the alkalinity of natural seawater, is best for fish tanks; > 3.0 meq/L is recommend for reef tanks.
The alkalinity is basically a measure of the capability of your aquarium water to resist changes in pH from the addition of acid (Trevor-Jones, Nov. 2002). Acid is continually entering the aquarium, primarily as the result of respiration (CO2) and metabolic wastes produced by the aquarium inhabitants (Trevor-Jones, Nov. 2002). The addition of these acids tends to lower the pH of the aquarium water. The higher the alkalinity of your aquarium water, the more resistant it is to such downward pH shifts (Trevor-Jones, Nov. 2002). The amount of buffers (primarily carbonate and bicarbonate) in saltwater determines the alkalinity, so the alkalinity in effect is the buffering capacity (Trevor-Jones, Nov. 2002). When the buffering capacity of the water is depleted, the pH becomes unstable. Alkalinity test kits can now warn of low buffering levels in time to prevent potential pH problems (Trevor-Jones, Nov. 2002).
Carbonate Hardness (KH): Optimum level = 7dKH (the hardness of natural seawater)
Carbonate hardness is another measurement of alkalinity. It is usually expressed in the German unit dKH (degrees of carbonate hardness) and is often considered to be the total alkalinity. (Dividing dKH by 2.8 will give you the alkalinity in meq/L.) KH actually a measurement of various carbonates and bicarbonates of calcium and magnesium within the aquarium water (Webber, 2004). Maintaining a stable KH is very desirable since it maintains the buffering capacity (i.e., alkalinity) of the system and prevents subsequent drops in pH. Aside from stabilizing the pH, reef keepers need to maintain KH and high alkalinity in order to assure that the calcifying organisms in the tank flourish. Corals and other calcifying organisms actively use bicarbonate, which is the main component of alkalinity, so the alkalinity of a tank with a lot of calcification can drop quite rapidly.
Calcium (Ca): Optimum level = 350 – 400 ppm (up to 500 ppm in well-stocked reef tanks)
Calcium is a very important element in the water in any marine aquarium and is a vital element in reef tanks. Along with carbonates and bicarbonates, it is required by calcifying organisms such as stony corals, snails and other mollusks, coralline, Halimeda and other calcareous algae, and certain sponges (Trevor-Jones, Apr. 2003). Calcium reserves must therefore be replenished on a regular basis. Regular water changes may achieve this, but reef keepers may require the addition of biologically available calcium to maintain adequate levels (Trevor-Jones, Apr. 2003). Seahorse keepers should be aware that brooding males provide calcium to the developing fry in their pouches, which the embryos probably incorporate into their skeletons. Deficiencies in calcium could thus adversely affect your seahorses’ reproductive success and the health of the fry. In fact, seahorses that receive a diet deficient in calcium often suffer from decalcification of their exoskeleton, a debilitating condition commonly known as "soft plate" disease (Greco, 2004).
In summary, some of the measures that will help control nitrates and phosphates (and excess nutrients in general), or which can otherwise help control nuisance algae in the aquarium are the following:
1) Make sure your protein skimmer is working correctly. A protein skimmer works 24 hours a day to remove excess waste and nutrients from a tank. If the venturi is clogged on a venturi skimmer or there is another problem with other skimmer designs, waste will not be exported from your tank and algae will take advantage of the waste.
2) Perform regular water changes. Regular water changes will decrease the level of wastes and nutrients in the water. But the water changes won’t do much good if your tap water itself contains phosphates and amines. Depending on how high the nitrate levels become, increasingthe proportion of water that you change each time may be necessary to help reduce those nitrates. There is an article about nitrate reduction at <<http://www.about.com/>> in the saltwater section that really explains water changes (gives you the math), on actually how little you are reducing nitrates with small water changes when you have high nitrates.
3) Make sure makeup water is pure. Phosphates and nitrates often found in tap water. Phosphate and nitrate test kits will show if your tap water is contributing to your algae problem. If phosphate and nitrate levels are more than 0 ppm (some tap water measures out at over 50 ppm nitrate), filter the water through a RO/DI unit before using it as makeup freshwater or as source water for saltwater changes, or purchase RO water from a vendor.
4) Add additional detritivores to your cleanup crew. If excess food isn’t eaten, it will decay and add to the nutrients and waste in the tank. More microhermit crabs, Nassarius snails and cleaner shrimp will help ferret out any uneaten Mysis before it breaks down and enters the nitrogen cycle to eventually end up as excess nitrate.
So if you’re having a problem with nuisance algae, consider bolstering your cleanup crew with additional snails and/or micro-hermit crabs that eat slime algae and other types of nuisance algae. Astrea snails, red foot moon snails, and Scarlet reef hermit crabs (Paguristes cadenati) all fit the bill and would be good additions in that regard.
Introduced as soon as possible to a new aquarium, as soon as the ammonia and nitrite levels are safe, Astrea snails effectively limit the development of all microalgae. In other words, they are good at eating diatoms, but will consume red slime and green hair algae as well. The Scarlet Reef Hermit Crab (Paguristes cadenati) is a colorful micro-hermit that’s a harmless herbivore. So cannibalism isn’t a concern at all for these fellows, nor are they likely to develop a taste for escargot. As hermits go, most of the time the Scarlet Reefs are perfect little gentleman and attractive to boot. I even use them in my dwarf seahorse tanks. Best of all, they eat all kinds of algae, including nuisance algae such as red, green and brown slimes, as well as green hair algae.
5) Introduce macroalgae to consume excess nutrients and nitrates. If regular pruning is done, fast-growing Caulerpa will maintain its color and high growth rates without going sexual. Better yet, an algal filter or "algae scrubber" can be established in a sump or refugium.
6) Chemical controls. Phosphate absorbers can remove excess phosphates, and Poly Filter pads can help absorb excess nitrates, changing color as they do so, which helps indicate= when the Poly Filter needs to be changed. Low ash activated carbon that is free of phosphates will also help remove such nutrients if it is change religiously and replaced with new carbon.
7) Controlled addition of food to tank. Don’t broadcast feed, scattering Mysis throughout the tank. Instead, target feed your seahorses or use a feeding station. Don’t overfeed, cleanup leftovers promptly, and observe fast days religiously.
8) Eliminate dead spots and increase the water flow in areas where the nuisance algae tends to grow.
9) Maintain the pH and total alkalinity of the aquarium in the proper range. Monitor alkalinity or carbonate hardness and the calcium levels in the tank as well as the pH.
10) Replace your aquarium lamps regularly to assure that the spectrum of light they put out favors the growth of coralline algae and macroalgae. (Over time, as bulbs age, they begin to put out light shifted more towards the red-end of the spectrum, which encourages the growth of hair algae.)
For more information, check out the following three online articles which are loaded with additional tips and suggestions for controlling outbreaks of nuisance algae:
Click here: CyanoControlFAQs
Click here: GreenAlgContFAQs
If you’ve are ready tried your best at cleaning things up, tuning your protein skimmer, and bolstering your cleanup crew, and the other sorts of control measures discussed above, Nigel, and if the slime algae stubbornly fails to respond to such measures in your case, there is one other product that can usually save the day. However, you must use it with caution, as discussed below:
If all else fails, stubborn cases of red slime algae (i.e., cyanobacteria) can be eradicated using a product called ChemiClean. It is designed specifically to get rid of Cyanobacteria and slime algae in the aquarium, and often works wonders when all other efforts to get rid of the red slime algae have failed. ChemiClean is not an antibiotic and it is safe to use in reef tanks; it is said to be safe for corals, invertebrates and fishes in general.
So one option would be to treat your aquarium with ChemiClean while the seahorses are in it. I know some hobbyists who have done so with excellent results and no harm whatsoever to their seahorse (Leslie Leto, per. com.).
However, I hesitate to suggest this product to seahorse keepers except as a last resort, Nigel, due to the potential risk of asphyxiation. Chemi-Clean evidently acts by oxidizing the organic "sludge and settlements" that accumulate in aquaria, in a process which apparently consumes oxygen from the water in much the same way as formalin does. That is why the online instructions specify that you add an airstone, preferably one with a wooden air diffuser, to provide efficient aeration and oxygenation of the aquarium when you use the product.
You must turn off your protein skimmer to use this product, which in itself reduces the aeration and oxygenation in the aquarium, and when this is combined with the oxidizing action of the Chemi Clean, which further reduces the dissolved oxygen level in the aquarium, it can create a dangerous condition for your seahorses due to the risk of asphyxiation. Seahorse setups in particular are susceptible to such problems because hobbyists are so conscious of their seahorses’ limited swimming ability that they tend to leave their aquariums undercirculated. Poor circulation and inadequate surface agitation can lead to inefficient oxygenation and insufficient offgassing of carbon dioxide.
Seahorses are more vulnerable to low O2/high CO2 levels than most fishes because of their primitive gills. Unlike most teleost (bony) fishes, which have their gills arranged in sheaves like the pages of a book, seahorses have rudimentary gill arches with small powder-puff type gill filaments. Their gills are described as "tufted" because they appear to be hemispherical clumps of tissue on stems. Their unique, lobed gill filaments (lophobranchs) are arranged in grape-like clusters and have fewer lamellae than other teleost fishes, making them a little less efficient.
So if you want to try ChemiClean while your seahorses are in the tank, be sure to add a least one airstone for additional aeration and oxygenation and observe all of the precautions in the instructions. Once you obtain the ChemiClean, perform a large water change and remove as much of the red slime algae as you can before you add the first dose. Remove your chemical filtration media but keep all your filters running so they roil the surface of the water and provide adequate surface agitation to promote oxygenation and facilitate efficient gas exchange at the air/water interface.
Then after you use the ChemiClean according to instructions and have performed the requisite water change, reinstall fresh activated carbon, and start your protein skimmer operating again. Please read all of the information at the following web site before you make a decision on whether or not to use the ChemiClean, Nigel:
Click here: Reef Show – CYANO BACTERIA: red-slime algae? Cause and Relief
Best of luck getting rid of that unsightly slime problem, Nigel! If you can eliminate excess nutrients in dissolved organic from your aquarium and restore optimum water quality during the process of eliminating the slime algae, your seahorses may well respond favorably and display renewed interest in courtship and breeding, and hopefully many broods of babies will soon be forthcoming.