If it's anything like what you see in the link below, then proceed down to what I did to eradicate it.
https://www.google.com/search?q=cya...bih=456#tbm=isch&q=cyanobacteria+in+reef+tank
I have tried two different methods, chemical and natural/biological. The chemical method which was chemiclean only masked the problem like James said, for a few weeks. Then I got myself a red and blue bulb off amazon and a big chunk of chaeto and ran the fuge for 12 hours when my main display lights are off. Oh and I also increased the flow/pressure coming from my return and now it's been months since i last saw that nasty slime.
That is all and don't anyone say I don't help on this crappy forum..lmao...j/k...or am I.. lmao <--- don't take it personal anyone but that is how I am going to finish off all my helpful posts from now on...lmao..j/k...or am i? rofl