Mother nature knows best: Seahorses and algae go hand in hand! Algae scrubbers for the win!

Excess nutrients can easily become an issue to anyone keeping seahorses.  Seahorses might be, in my opinion, the most magical and awesome fish to ever be kept in an aquarium, but they do eat more often, require more fatty foods that make a huge mess when they aren’t eaten, and because ponies seem to “redistribute” the food as waste almost as quickly as they eat it, the nutrient levels within the tank can get out of control very quickly. High nutrient levels can lead to a build up of bad bacteria and pathogens, which will harm the seahorses.  While there are microbial organisms in every system, many will only become pathogenic in high nutrient or poor water quality situations. Mother nature was thinking of the animals when she decided to make algae grow as a natural way to eliminate some of the nutrients that can build up and lead to situations which harm the animals.  I personally adore the look of colorful macro algaes in a tank and give mother nature a thumbs up every time they lower my nitrate and phosphate levels. *(you may have to click on the arrows to view my slideshow of pictures)

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But, some of those macros do not grow fast enough to keep up with the “seahorse level” of waste, and the slimy algae that grows when nutrients surpass the filtration methods of a tank are just not as pretty.  When the “bad algaes” outcompete the macros for food, it’s heartbreaking.  Who wants to see this when admiring their seahorses?

Or even worse, is seeing the bad algae grow on the actual seahorses!

Every single time I’ve personally experienced a problem in my seahorse tanks, such as weak snick, gbd, and a flesh eating bacteria, I could directly attribute the root causes to issues with water quality, typically stemming from high nutrients.  Whether a skimmer broke, or I was slacking, there was never any shocking illness, in which the root cause wasn’t obvious.  Maintenance tricks like cleaning up any uneaten food quickly, running a skimmer, keeping macro algaes in the tank, and staying on top of water changes can help keep nutrient levels low, but I try to give credit where it is due, and my algae scrubber deserves quite a bit!  Growing algae in the sump allows me to use the brilliance of Mother Nature’s filtration, without having to see it all the time! The benefits I’ve noticed since adding an algae scrubber designed by a friend (Ronald Chinners) include:  lower levels of phosphate and nitrate, less physical work during water changes, less unwanted algae in the display tank and on the seahorses themselves, an increase in copepods, stable ph in spite of high co2 conditions, no ammonia creeping up when I had to remove half of my rock to treat for aptasia (1/2 rock = 1/2 biological filtration) and healthier seahorses.

scrubber full sump 2

While most people do everything they can to rid their saltwater tanks of algae, I am constantly trying to add more!  Algaes aren’t always pretty, but they are a natural response to high levels of nutrients.  The first, and in my opinion most important, benefit to my algae scrubber has been the reduction in the nitrates and phosphates, which contribute to high nutrient levels.  Before I added my scrubber, I was doing 20% weekly water changes, and still the tank would be creeping towards a nitrate level of 20 by the end of the week.  Considering that most professionals recommend keeping nitrate levels below 10, and long term high nitrate levels can harm seahorses, I wasn’t doing my ponies justice.  Phosphate levels have very little wiggle room before you start seeing the unwanted response of “bad algaes” form to consume them. The redfield ratio of proper balance between nitrate and phosphate is very important and is thrown off if either gets too high, low, or out of balance in relation to the other. (The redfield ratio is fascinating, and I’ll discuss this much further in future blogs, but for now, there’s always google if you want to learn more :)),

When using macro algaes in a tank, you want SOME nitrates and phosphates for them to “eat”, but finding the balance between feeding macros and keeping seahorses healthy can be difficult.  Unfortunately, because seahorses are such “nutrient creators”, I was already spending an entire day every week doing not only a water change, but also scrubbing walls and floors, clearing the ugliest of algae from rocks, and basically breaking my back just to keep the levels livable.  I couldn’t stand the ugly algae growing all over my pretty macros, perfectly placed rocks, and even on the seahorses, but knew it was just a response to the high nutrient levels.  The algae was growing BECAUSE my tank was feeding it.  I couldn’t feed the seahorses less, and finally realized that if I just moved the algae growth out of the display tank, I could use it’s help without hating the site of my tank!

The algae scrubber that Ronald designed for me is quite cool!  My overflow leads directly to a sectioned off portion of my sump, which contains the acrylic “box” that holds my algae screens. The tubing from the overflow is attached to a lid by way of a 1″ bulkhead. scrubber full with mesh

Ronald wisely mimicked an overflow box, using notches in the sides of the top of the acrylic, to prevent the water from overflowing the sump, if I happened to use a pump that was too high pressured, or any other possible disasters that might lead to a flood.

At the top of the contraption, directly under the lid, there is a removable “shelf” or drip tray, with many holes drilled into it.

The holed piece is covered with filter floss to catch large particles, and performs the first in a series of “filtration”. After the water travel’s through the floss, it drips through the holes onto 2 detachable or adjustable acrylic pieces that force all the water to the center, so that it will drip down onto an upside down V shaped piece of acrylic, which holds the mesh screens.

This allows the screens to get equal amounts of water flowing over them, at a trickled rate, so that the algae on the screen is exposed to both water and air (wet/dry). Below the screens is a big empty space that could hold rubble, bio balls, rock, media, or whatever tickles my fancy.  I usually put a bag of purigen or other media in the water below, along with rubble to promote copepod growth.

There is a hole in the sides of the “box” allowing the water to travel into the other parts of the sump, after it is run over the scrubber screens.  Two 5000K lamps with black backing (to keep the light going only where I want it) are set directly outside the sump, pointing at the screens.  Warm light in the 2700-3000K range would make the algae grow faster, but I don’t want it to work too well, and out-compete my display macro algaes.  A minimum of 23 watts is recommended to provide enough light to keep the algae happy.

The light mixed with the trickled water grows algae on the screens. The algae below is more slimy than usual, because I cleaned the sump right before vacation.  I wish I had taken pictures prior, as the screens are typically covered in bright green, fluffy algae.

This algae will not only consume large amounts of nutrients like phosphate and nitrate, keeping the display tank clearer, but running the lights on a reverse light cycle has evened out any ph shift at night.

Plants, including macro and all types of algae, produce oxygen and absorb co2 (carbon dioxide) as part of the process called photosynthesis (using light to turn water and carbon dioxide into glucose/food). This is very beneficial to an aquarium under normal circumstances, and helps oxygenate the tank.  However, when there is no light present at night, plants go through a process called respiration, in which they take in oxygen and give off co2.  When co2 is dissolved in water it becomes h2co3 (carbonic acid), which lowers ph.  This is one of the reasons we see the ph in an aquarium drop at night.  Ph levels that are too high or low, or have tremendous fluctuations, can hurt the aquarium in many ways including: interfering with fish’ reproductive cycle, increasing the toxicity of ammonia, increasing the solubility of phosphorus and other nutrients, and eventually affecting the skin or slime coat and gills of the fish, leading to asphyxiation and/or death. There is no way to keep ph constant, and “chasing PH” (using additives and or trying to change the chemical make up of the tank in order to keep ph at a constant 8.3) is a losing battle. The normal rise and fall of ph within water is normal and not typically a concern.

However, if you have other factors affecting the co2 levels, for instance smoking, high co2 levels in the home due to not opening windows often, a large number of fish (their respiration creates co2), traces of ammonia, decreased calcium levels and/or low alkalinity levels, the shifting ph could become a problem.  Increasing surface agitation can help oxygenate the tank and drive off co2, but if the oxygen levels in the home aren’t good, more might be needed to fix the problem.  An algae scrubber on a reverse light cycle (meaning the light on the algae scrubber in the sump comes on during the evening time that the display tank’s light is off) means that there are always plants performing photosynthesis and giving off oxygen.  This offsets the natural lowering of the ph due to sleeping plants and coral in respiration in the display.  I personally have central air and rarely open my windows, so co2 and ph have always been a concern for my aquariums.  Adding the algae scrubber on a reverse light cycle using an inexpensive outlet designed to turn lights on and off at the times I have programmed, has helped tremendously in keeping the ph levels in my tanks stable, and the fluctuations from being too great.

All at once, this scrubber fixed many issues I was having with my tank, and I just love all the benefits it has provided!

The way algae works (whether we’re discussing the ugly type we don’t want, macro algaes, or the algae on a scrubber) is that consuming nutrients makes it grow. When our tank’s are full of excess nutrients, we will see algae grow to compensate. Therefore, we want the algae on the scrubber to continue to constantly grow, and can accomplish this goal by trimming the algae.  Just like the old wives tail about human hair, algae will grow faster when trimmed, and will stall in growth if it gets too long or thick.  It’s also amazingly satisfying to hold the organics and inorganics of your tank, literally in your hand, and throw them in the trash! That’s exactly what happens when we throw away the trimmings, because they are holding everything the algae has consumed.  When the scrubber is first installed, it will take a good month to grow to a length that needs trimmed.  After that, trimming needs to be done every week, to keep the scrubber working efficiently.  I’ve been known to forget, but my tank sprouting algae is a quick reminder!  I’m also careful to remove the screens and trim them in the sink, to avoid any spores or pieces of trimmed algae making their way back to the display.

There are many algae scrubbers on the market, and even more diy options to make your own.  I love this design and would suggest contacting Ronald to anyone, because it works very well, and the 2 screens mean I never have to go through the “break in” time again!  When a scrubber is first set up, I’ve already mentioned it will take a little time to start growing algae, but I’ll also warn that it will go through a “start up” phase of brown slimy algae.  Some people choose to leave that algae, and the green algae will eventually grow on top of it.  Some clear that algae until the green takes over. Either way, never clean the screens completely, because you’d be starting all over again.  If black, or very dark brown, slimy algae grows, but doesn’t seem to continue growing, it typically means you need more lighting or a longer photo period. Yellow growth indicates too much lighting or the need to shorten the photo period.  It could also indicate that your system is low on nutrients (not likely with us seahorse folks, haha). Trimming the algae weekly, even it doesn’t appear to need it, ensures that your scrubber will keep working. Initially making the screens rough by rubbing them against cement will provide little jagged edges that will catch debris and tiny pieces of algae, and help start the growth.  Or even adding pieces of the algae in the display, that you would prefer grow in the sump, to the screens can get the growth started a little more quickly. With a scrubber containing 2 screens like mine, I can completely clear one screen if I want to, and always have a full screen of algae consuming nutrients.

Whether you decide to buy a scrubber or make one, it’s important to follow the guidelines regarding size and lighting.  Too large an algae scrubber could result in any plants or coral in the display tank suffering due to lack of nutrients.  Too small a scrubber will just keep growing the brown slimy algae, and never provide all of these wonderful benefits. suggests 1.0 square inches of screen per gallon if light is placed on both sides, 2.0 sq in if lit on only one side, and 4.0 sq inches if horizontal.  Lighting recommended is .5 actual fluorescent watts per gallon minimum and 1.0 watts per gallon for high filtering (that’s us folks). Others base the size of screen on the amount of food the tank receives, but considering this is a seahorse article, we’ll just bypass any thought of small feedings. The light should be within 4″ of the screens, with a maximum of 6″ before it won’t work.  If CFLs are used, they should be replaced every 3 months, while LED lighting will last longer. But always replace the lights BEFORE the manufacturer recommendation, because the amount of light lessons as it’s used, and the algae will suffer before people would notice the difference.

copepod.jpgThe pods, oh the pods! An algae scrubber is a perfect way to increase the copepod population within an aquarium. This is because they live in and feed on the algae growth on the screens.  In fact, they like my algae scrubber so much, that I shake the screens over the display every few weeks, to prevent them from consuming all of my algae, and provide a tasty treat to any seahorse that can actually see them!  A healthy pod population within a tank is very important to overall success because they are a key part of the ecosystem, they feed on microorganisms, and are a food source for many inhabitants.  Even people without nutrient woes might consider an algae scrubber just for the added benefit of the pods that grow in it. I’m considering using a sieve type mesh to divide the scrubber from the rest of the sump, and try to start a mysid population. Because I run an inline UV on the return to my h.erectus display, I really should have tried to place the scrubber above the tank, so pods and other critters could safely make their way to the display.  But, shaking the screens and possibly dividing the sump has worked very well for me so far.

Also, with a scrubber versus a refugium, you avoid the critters you DON’T want as part of your ecosystem.  The ones that might be good for an aquarium itself, but not so much when dealing with ponies.  It’s pretty cool to avoid the detritus build up too!

bristleThe benefits to an algae scrubber are almost too numerous to list.  While many pieces of equipment can be helpful in controlling nutrients within a seahorse tank, not many remove the amount of inorganic nitrate and phosphate that a scrubber will.  I always tell new seahorse keepers that a skimmer is a crucial piece of equipment in setting up for seahorses, and stand by that instruction, but even a skimmer only removes 20 – 30% of organics, and doesn’t touch inorganic nutrients. Both oxygenate the tank, but the scrubber also removes heavy metals like copper and iron, minimizes ph swings, promotes pod growth, and doesn’t store phosphates and promote detritus as seen in a refugium.

I took no direct quotes, but did use the following sites to double check my knowledge. These articles go into further detail about scrubbers:





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