Cyanobacteria

• Cyanobacteria AKA red slime algae has to be one of the most difficult problems a marine aquarist has to deal with, first of all it is not an algae but a bacteria, but like algae contains chlorophyll that enables it to carry out photosynthesis, additionally cyano has the ability to pull organic compounds directly from the substrate and water enhancing their ability to thrive and making it so problematic.

• Cyanobacteria AKA red slime algae are misleading since it sometimes appears and is AKA known as blue-green algae. Cyano can appear red, blue-green, brown, black, mustard yellow, depending on lighting. Cyano produces and traps oxygen bubbles, which will lift it in sheets to the surface in severe cases, so if what you have contains many bubbles it is probably Cyanobacteria.

• Cyano usually appears in the first few months because of high organic levels from curing live rock, it usually disappears when tank matures. It will easily come back though if maintenance is neglected or if the tank becomes overstocked, overfed, dead fish left in tank, basically increased nutrients.

• Watch for increased nitrates and phosphates a sure sign of nutrient level increase.

What to do

• Don’t give up even though this can wreck havoc on your system, Attack with as many simultaneous methods as possible

• Control feeding

• Stop bottled invertebrate foods until cyano controlled

• Check phosphate & nitrate levels

• Water change weekly 20 –30 %

• Use Di or Ro water for water changes if possible

• Manually siphon any visible detritus from substrate

• With a toothbrush manually remove cyano from live rock and net or siphon out of tank.

• Use a protein skimmer - one of the most effective methods of removing organics, if you run skimmerless consider adding at least until you have the upper hand on cyano.

• Make sure skimmer is large to accommodate your system – Always oversize

• Clean skimmer daily making sure the cup and importantly the barrel is residue free or the organic soup wont get up into the dump cup.

• Lighting may play a minor role – change bulb spectrums if having no success

• Add snail and hermit crabs - (lots) hermits will eat it and some marine snails will also.

• Change carbons and poly fibers (alternately) biweekly or even weekly removing as much organics as possible.

• Add phosphate / nitrate absorbing media bags

•Begin calcium hydroxide (kalkwasser) drips, which will help, bind phosphates and increase skimmer performance.

•Upgrade circulation pumps if you do not have good circulation. Poor circulation leads to detritus deposits

• Check sump for detritus, remove by siphoning or netting

• If all else fails treat with antibiotics like erythromycin. There are products that are designed to eradicate red slime algae, most containing antibiotics. Be aware that It will not be selective in which bacteria it will eradicate, so with the cyanobacteria you will also loose your good bacteria responsible for ammonia and nitrite conversion. Tip - store some of your filter media with bacteria in a separate container and put back in your system after treatment.

• Good luck – expect changes to take place slowly but progressively

Rick L

References - Marine reef magazine 2005

- Marine Aquarium – Nick Dakin