Dear Sue:

Pete Giwojna

Dear Sue:


Thanks for getting back to me with the additional information, Sue! It’s good to hear that the cyanobacteria has not made a reappearance because it is much more difficult to eradicate than the diatoms are.


I don’t think that you are overfeeding, Sue, but for best results I would increase the amount of frozen Mysis you feed and reduce the amount of brine shrimp. Overall, the frozen Mysis are far more nutritious, so feeding a 50/50 ratio of frozen Mysis to brine shrimp is probably not the best approach for a seahorse tank.


Of course, it’s important to diversify the diet of the seahorses, so I can certainly see why you are including the brine shrimp in your feeding regimen, Sue, but I would rather that you accomplish this by choosing two different brands of frozen Mysis with different nutritional profiles and then providing the ponies and gobies with one feeding from each brand of frozen Mysis instead. I like to use Piscine Energetics frozen Mysis relicta, which are a freshwater species harvested from glacial lakes in Canada, and that therefore have a unique nutritional profile, together with a different brand of frozen Mysis that is of marine origin and then alternate those two brands when I’m feeding my ponies.


And always make sure that you gently but thoroughly rinse the thawed Mysis to remove the excess shrimp juices before you add it to the aquarium and feed your seahorses.


Having your current water quality readings is very helpful, Sue. For starters, it’s plain to see that the pH, water temperature, specific gravity, and levels of nitrite and nitrate are all excellent and are not contributing to the problem with nuisance algae in any way.


But the ammonia reading (0.25) and the level of phosphates (0.5) are too high and we will want to correct those as soon as possible. Once we have lowered the ammonia to zero and reduced the phosphates as much as possible, thereby restoring optimal water quality, it is very likely that the diatoms will soon disappear for good and that the cyanobacteria (red slime algae) will no longer recur.


Of the two, the ammonia is the most dangerous and also the easiest to control, Sue, so let’s start with that.  In my opinion, one of the most important steps that the home hobbyist can take when preparing a new saltwater aquarium is to cycle the tank using a product such as AquaBella Organic Solution or SeaChem Stability, and one of the most important steps they can take when maintaining their aquarium thereafter is to include monthly boosters of the AquaBella or Stability to help maintain optimum water quality thereafter and assure that the biological filtration in the aquarium is functioning at maximum efficiency.


Not only will cycling a newly established aquarium using SeaChem Stability or AquaBella Organic Solution greatly accelerate the cycling process, it provides the aquarium with denitrification ability as well as the usual beneficial nitrifying bacteria. That is extremely important because the anaerobic, heterotrophic, and facultative bacteria included in the AquaBella or in the SeaChem Stability will give the aquarium the ability to complete the nitrogen cycle, not only converting deadly ammonia into nitrite and then breaking down the nitrite into relatively harmless nitrate, as usual, but then taking the process a step further and converting nitrate into nitrogen gas (N2) that bubbles out of the aquarium into the atmosphere and is removed from the tank entirely. That prevents nitrates from accumulating in the aquarium, which is very important for seahorses and delicate invertebrates that are sensitive to high nitrate levels.


Furthermore, the ability of the heterotrophic bacteria in either the SeaChem Stability or AquaBella Organic Solution to break down phosphates, detritus, waste products, and the grunge that accumulates in the substrate over time and prevents organic wastes from accumulating in the aquarium is especially helpful for keeping seahorses, which have specialized aquarium requirements, healthy and happy in the long run.


Adding the proper dose of Seachem Stability to your aquarium for seven consecutive days will assure that your ammonia reading his back down to zero and stays there, Sue, as well as helping to reduce the levels of phosphates. So let’s start with the Stability and go from there.


Getting the water quality back to optimum condition – especially the level of silicates and phosphates – will be very helpful in eliminating the brown algae or diatom growth in the long run, Sue, as discussed below:


Diatoms in the Aquarium


Diatoms are generally harmless and most newly set up marine aquariums go through a stage where the diatoms or brown algae grows on surfaces in the aquarium.  In most cases, the brown algae will disappear as suddenly as it appeared once it uses up the available supply of some key nutrient in the aquarium (usually silicates).  Ordinarily, once the available silica has been exhausted, the population of the diatoms will crash and they will then typically die off on their own. 


If not, there are some other simple measures you can take to help eliminate the brown algae.  As I said, brown diatom algae is usually the first problem algae that a new marine aquarist encounters. A bloom of brown algae often occurs soon after the saltwater is added and the tanks begins cycling (because artificial salt mix contained silica) or after one introduces new live rock to a marine aquarium. This bloom occurs because the curing of the live rock introduces silicates and nutrients (even pre-cured live rock from your LFS will have some die off after it is transferred to a new aquarium; that’s normal).  As a result of the diatom bloom, a brown film soon coats everything inside the tank.


Most likely, Sue, all you need to do to eliminate the brown algae or diatoms is to wait. Time is your ally in this instance, and once the diatoms deplete the available silica levels, their population will crash and they will disappear, as explained below:


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Diatom Algae typically is brown in appearance and usually is seen within the first 4-16 weeks following the install of an aquarium. Diatom algae have three basic needs to thrive: silicate as a food source, a low pH in a saltwater environment, and light in the yellow, orange, and red spectrum. During the first few weeks after an aquarium is set-up diatom algae growth can be very aggressive. It may cover the glass in as little as 48 hours. Diatom algae growth is normal and the direct result from the tremendous amount silica found in the synthetic salt used to make saltwater. Most synthetic sea salt manufacturers use silica, a moisture removing product, in the manufacture of synthetic salts. As the concentration of silica falls, the algae runs out of food, and slowly goes away.

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So for now, just be patient, Sue, and your brown algae (diatom) should eventually clear up on its own. (However, I would hold off on the frequent water changes you have been making for now. It is quite possible that you are replenishing the silica levels with the makeup water or the newly mixed saltwater you add to the aquarium, and that’s why the brown algae or diatoms tend to reappear with a vengeance every couple of weeks. You can also hasten the process by bolstering your cleanup crew with aquarium janitors and sanitation engineers that like to feed on diatoms.


Control of brown diatom algae is relatively easy. The first thing to do is to purchase several more snails that are known to feed on diatoms, such as Cerith snails, Trochus and Astraea snails. Those are all types of snails that eagerly consume the brown diatom film. There are other snails that will clean the glass such as Nerite and Strombus snails, but Trochus and Astraea and Cerith snails are the brown diatom cleaner workhorses. (Among the microhermit crabs, the red legged hermits have a taste for diatoms and can also be very helpful in controlling a diatom bloom.)


Adding some snails are microhermit crabs that love to feast on diatoms should help get the problem under control, Sue. If not, the next thing you need to do is to perform regular water changes using RO/DI water only (well water and tap water can sometimes contain significant amounts of silica) to remove any excess nutrients and silicates from the water. The third thing to do is to have well-tuned, efficient protein skimmer operating 24/7 to help with the nutrient removal. The final thing to do is to have some type of chemical filtration such as Rowaphos or Phos-Zorb to help with the nutrient removal.


Be sure to load up on some of the Trochus and Astraea and Cerith snails that love to feed on the diatoms and to introduce some Rowaphos or Phos-Zorb to the chemical filtration compartment in your aquarium filter, Sue.


Here is some additional information on the Rowa phos that explains what it does and how to use it properly:


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Rowa phos


*           Premium phosphate-removing chemical filter media for aquariums

*           Binds phosphate without releasing it back into aquarium water

*           Effectively lowers phosphate levels in fresh or saltwater aquariums


The ultimate phosphate removal media for freshwater and saltwater aquariums. Originally developed in Germany to treat water supply mains, this unique and patented ferric hydroxide media is chemically engineered for efficient removal of phosphate, arsenic, and silicate. Rowaphos binds aquarium pollutants and does not release phosphate back into the water even when exhausted. Increased concentration of the aquarium pollutant phosphate can contribute to unwanted conditions including aggressive nuisance algae growth and inhibition of calcification in such marine organisms as calcareous algae and hard corals. Use Rowaphos to effectively remove phosphate and improve aquarium water quality. The binding (adsorption) capacity of Rowaphos is approximately 25 grams phosphate per kilogram of media.


Suggested Use

            Freshwater                    Saltwater

100 ml Up to 200 gallons          Up to 100 gallons

250 ml Up to 500 gallons          Up to 250 gallons

500 ml Up to 1,000 gallons       Up to 500 gallons



Rowaphos can either be used in a canister filter as a separate slow phosphate filter or can be utilized at the end of the main filter system as the final stage after the biological and mechanical filters. The material can either be used in filter bag or sandwiched between two layers of fine filter pads (on the incoming and outgoing flow).


To reduce the phosphate level in the water column by approximately 3 ppm phosphate measured as (PO4) use:

            Freshwater        Saltwater

100 ml Up to 200 gallons          Up to 100 gallons

250 ml Up to 500 gallons          Up to 250 gallons

500 ml Up to 1,000 gallons       Up to 500 gallons



The amount of Rowaphos required will be determined by both the level of phosphate in the water column and the level of phosphate in the rock, gravel and other substrate in the aquarium. The above chart is for maintenance use on aquariums where the phosphate level within the substrate has already been reduced. On new or established aquariums where the phosphate levels are high, first measure the level in the water and assume 2-4 times that amount may be bound in the substrate. Adjust the recommended amount (per above chart) by dividing aquarium size by 2-4 times.


The lifetime of the filter material, like the usage, depends entirely on the PO4 concentration in the aquarium. Regular checks with a precise and reliable phosphate test will show the extraordinary effectiveness of Rowaphos. In addition, it will indicate in advance when the filter material is due to be changed.


Rowaphos can work for several months in the aquarium before replacement is required, depending on the initial phosphate concentration and level of feeding. It is important to remember that with an established aquarium that has not used Rowaphos before, phosphate concentrations may be at exceptionally high levels of 5 ppm or more requiring several times the quantity specified above to remove the phosphate from the water column and to eradicate levels absorbed into the substrate and rocks.


Use Rowaphos immediately when setting up a new aquarium. This ensures that no high PO4 concentration can arise in the first place. To eliminate phosphate successfully, it is necessary to use Rowaphos in a new or matured aquarium on a permanent basis.


Note: Do not rinse Rowaphos before use! In some cases the use of Rowaphos can turn the aquarium water slightly brown in color due to the dislocation of finer particles of the material. This is completely harmless for fish or any other organisms and will disappear after a short period of time.


Always replace the lid of the Rowaphos container after use.


Tips on Rowaphos

To obtain the best results from Rowaphos and to keep your aquarium at zero phosphate levels, it is important to use Rowaphos at the startup of a new fresh or saltwater aquarium. Phosphate is released from both gravel substrates and live-rock. Therefore, it is very important at the early stage of the aquarium to remove the phosphate immediately to reduce potential nuisance algae blooms.


Rowaphos will adsorb phosphate, silicate, and arsenic and is entirely safe in both fresh and saltwater systems. It does not release any of the absorbed materials back into the aquarium even when fully loaded.


Rowaphos only needs replacing when the phosphate levels in the aquarium or at the outlet from the canister filter start climbing. This indicates that the Rowaphos have absorbed phosphate to its full holding capacity.


During use of Rowaphos, you will see no ill effects. Additionally, if you are using Rowaphos in a saltwater invertebrate aquarium, hard and soft corals may grow up to approximately three times as fast when phosphate levels are below 0.015 ppm.


    Never wash Rowaphos for non-fluidized use.

    Rowaphos must be kept damp at all times as its effectiveness is significantly reduced if allowed to dry out. Always replace the lid if not using the entire container.

    The media can be used in a mesh filter media bag or sandwiched between two layers of mechanical filter media in a canister filter.

    Do not sprinkle Rowaphos directly into the aquarium.

    Never place Rowaphos directly into water without first surrounding it with sponge or floss.

    When used in a canister filter, the flow should be adjusted until zero phosphate level is achieved.

    It is important that the filter media bag is clean at all times. Otherwise, water will not flow through the Rowaphos media inside.

    Use of larger quantities of Rowaphos may temporary lower the pH within the aquarium.


Phosphate Levels and Testing In marine systems, phosphate levels should always be maintain below 0.015 ppm (when measured as phosphorous ‘P’, 0.046 when measured as phosphate ion ‘PO4-‘. In freshwater systems and ponds, phosphate levels should be less than 0.03 ppm ‘P’ and 0.092 ppm ‘PO4-‘).


Fluidizing Rowaphos

For simplicity of use and to maximize the life of the media, it is recommended to fluidize Rowaphos in a fluidized chemical media reactor. This method makes the entire media surface area available for adsorption from the water stream. Important: Take care not to over fluidize the media. When fluidizing Rowaphos, it is recommended to flush the media through in the chemical media reactor with fresh or reverse osmosis water to remove any fine particles that would otherwise temporarily discolor the aquarium. The fine particles are not harmful but may be seen by some as unsightly if it settles on the base of the aquarium or on rocks (Please note: This advice is contrary to that given for normal use in a media bag or canister filter where it is recommended that Rowaphos is used unwashed).


To Flush the Media:

First place the media in the fluidized chemical media reactor and connect the reactor to a freshwater supply. Slowly feed water through the unit being careful not to over fluidize the Rowaphos. Discard the brown water that first exits the reactor. When the water starts to clear, switch off the water supply and carefully tip the reactor to remove any excess freshwater above the media. Connect the chemical media reactor to a pump and carefully turn on the pump. Adjust the flow rate until the surface of the Rowaphos just starts to move. Any remaining discoloration of the water will quickly disappear.


General Information

Rowaphos is a completely new filter material for eliminating phosphate. Due to its unique chemistry, it has an outstanding ability to bind large quantities of phosphate by absorption to its surface without negatively influencing the water in the aquarium in any way.


Phosphate (PO4) in the aquarium is caused by the decomposition of organic substances. In the confined habitat of an aquarium, several of these decomposition processes take place on surplus food, dead plant and animal matter, animal waste, etc.


Phosphate is an important component of life, which is harmless only in low concentrations. Natural waters that have not yet been polluted by human intervention show very low PO4 concentration. However, it is nearly impossible to maintain this ideal condition in an aquarium without artificial aid.


An increase in concentration leads to unwanted conditions including aggressive nuisance algae growth and to the inhibition of calcification in certain specialized marine organisms, such as calcareous algae and hard coral. To remedy these phosphate-induced conditions, it is recommended to always keep the concentration of phosphate at or below 0.1-0.3 ppm in freshwater systems and in saltwater systems, it should always be kept below 0.015 ppm.


This target level can be easily achieved with Rowaphos. This highly active filter material can be used in freshwater as well as saltwater systems. Rowaphos binds PO4 without negatively influencing aquarium water. When exhausted, Rowaphos does not release phosphate back into the water. Rowaphos can and should be used in aquaria with sensitive fish such as Discus or in marine aquariums with complex organisms.

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If you cannot get the Rowaphos locally, Sue, then Phos-Zorb will also be very helpful for controlling diatoms or brown algae.  (Phos-Zorb by Aquarium Pharmaceuticals is a special filtration resin that removes both phosphate and silicate ions from saltwater.)


Best of luck getting rid of the diatoms and cyanobacteria for good, Sue!



Pete Giwojna, Ocean Rider Tech Support

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