I cut and pasted a section out of a algie control doc hope it helps I found when I had a problem with it it was due to poor water circulation I siphoned most with a turkey baster then got more powerheads and pionted them were the slime started and it went away if you have both cyanao and diatone I would check your phospate also are you useing ro/di water ??
Red Slime Algae - Cyanobacteria
Red Slime Algae or Cyanobacteria seem to appear out of nowhere.. Some of the contributing factors are.. Poor or incorrect lighting conditions, tanks that are high in Nitrate and or Phosphate, tanks that have a large bio-load and excess organics and poor quality protien skimmers or skimmers that have not been cleaned in a few months..
Cyanobacteria starts off as a small spot or discoloration from bluegreen to dark red and sometimes almost black in color that slowly forms a sheet or mat that rapidly spreads out from the localized spot.. Usually found in an area of low water flow and or low light.. This sheet or mat doesn't attach very well (thankfully) and is easily removed with a syphon hose and certainly should be removed to stop it from spreading.. After removal increase water flow in that area to stop it from reappearing..
Getting rid of Cyanobacteria..You should begin using RO or DI water for all future top-off, kalkwasser addition and water changes.. A few 10-20% water changes (with RO or DI water) will help to dramatically reduce the amount of nutrients present.. You should syphon off as much of the red slime as possible when doing water changes.. The addition of fresh activated carbon helps alot by removing excess organics and impurities from the system.. Use the fresh activated carbon for 3-4 days and then dispose of it (reusing the activated carbon can reintroduce the problem).. Clean your Protien Skimmer and replace the diffuser or clean out the venturi line, whichever is applicable.. If the problem persists, your Protien Skimmer is either undersized for your set-up or is not working effeciently enough to do the job properly.. Change your flourescent lights every 6 months to maintain the correct color spectrum.. Cyanobacteria in an established or mature set-up can also be removed by adding 1-2 cup of substrate or livesand (per 50 gal) from an established set-up (that is not infected with cyanobacteria)..
