Cyanobacteria (Red Slime Algae) and the importance of regular aquarium maintenance

Posted by on Oct 24, 2013 in aquarium service ma, Aquatic Community, customer service, General Information, Live Rock, medical, pH, Problems, Red Slime Algae (cyanobacteria), testing, Uncategorized, vacation care | 0 comments


Many reefkeepers are unfortunate enough to have encountered red slime algae in their aquariums and fish tanks. Many of us have encountered red slime but what is it and what causes it to grow?


aquarium maintenance MA


Red slime algae is not actually an algae at all, but rather an ancient form of bacteria called cyanobacteria. Cyanobacteria are marine, unicellular, photosynthetic organisms that have the distinction of being the oldest fossil on record at 3.5 billion years! Though they are unicellular, they often grow in colonies and can form a layer or “carpet” on surfaces such as sea beds and rocks.



red slime prevention by Imagine an Ocean

That’s great and all, but what is it doing in my tank?

That’s great, but what is it doing in my tank?


Red slime likes to grow in home aquariums where there is low water flow, where there is an abundance of waste or sunlight, and in water where there is low alkalinity. Cyano also thrive in environments rich with phosphates, nitrates, or iron.




To prevent cyano growth it is important to keep your water in pristine conditions (having an aquarium service provider certainly helps). Avoid overfeeding your fish! This can’t be stressed enough. You also want to avoid having “dead spots” where there is no water flow in your aquarium. Maintain regular water changes and make sure that your nutrient levels are appropriate. If possible, use RODI water, as tap water usually contains many elements that encourage bacteria growth. Lastly, if your water conditions are not ideal, do no expose your tank to an overabundance of light. This can make a small growth problem exponentially worse in short time.



Removing red algae can be tricky. Large swaths can be scraped off the glass, or if you’re lucky, off of your live rock. Using the known causes of cyano outbreaks (too much waste, too much light, not enough flow), try to diagnose the problem in your unique aquarium. Is there only a small patch in a secluded corner of your rock formation? Try adjusting your flow or your aquascaping to ensure that there are no “dead spots” that might foster a bloom. If your Alk levels are low, introduce more to your tank and keep levels high in the future. Too much waste? Cut back on the fish food and look around for any dead and decaying fish or corals. A dead body in the confined environment of a home aquarium is pure pollution of every kind; physical, chemical, and biological.



Though red slime algae is a bit of a misnomer, cyanobacteria thrive under similar conditions as their eukaryotic cousins, hence the confusion. By keeping an eye on your aquarium, and by keeping the water clean and conditions ideal, the home aquarist should have little trouble keeping his tank free from red slime. Regular aquarium maintenance is key, and if your tank is serviced by Imagine an Ocean, we promptly take care of any outbreaks and restore your tank back to its pristine beauty. For more info and pictures of our top-notch aquarium service in action, check out the photo gallery on our Facebook page!



Thanks for reading!