What is this stuff?


New member

I'm new to the Aquarist life, and don't know much. I have a 90 gallon SW tank that I hope will become a beutiful reef tank someday.

Lately I've had some things growing in my tank that I am clueless as to what they are.

This first one is kind of wispy, started on one piece of live rock but now seems to be appearing other places around the tank:


The second is appearing at various places in the sand:


Any info on what this stuff is, and what I should do about it would be greatly appreciated.

Looks like cyanobacteria to me. The stuff is not good, it can take over a tank quickly. How old is your tank? It is common to get cyano in a new tank. It feeds off of excess nutrients (phosphate and nitrate mainly). What are the nitrates and phosphates testing at? I think more flow also helps control the stuff, but there are different opinions about that.
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The tank is about 6 months old.

My water seems to test fine:
NO3 = 0ppm
NO2 = 0ppm
Alkalinity/Buffering capacity = 240
PH = 8.4

I have almost no water flow, just the filter and return. I do have a bunch of extra pumps though, would that help?

Any suggestions on how to get rid of the cyanobacteria?