stringy brown algae

[beeven]

Friends,

I have noticed a brown stringy algae (looks like my GF's hair) popping up all over my tank. Its growing on the substrate, on the LR, and in some cases the coral. Its easy to scrub off but its super annoying as it comes right back. I'm assuming it has something to do my water chemistry, however, all readings seem ok:

Nitrates - 0
Nitrites - 0
Ammonia - 0
PH - 8.1
SG - 1.026
Temp - 81

I use RO/DI water but admittedly I have not changed the filters or membrane on the unit since I bought it... purchases about 75 gallons ago. Keep in mind, however, that the Washington DC water is horrible.

Any advice or insight on what might be causing it to grow and how to eliminate it would be appreciated. Thanks in advance.

 

[Bebo77]

phosphates... and what kind of lights do you run.. how old is the bulb?

 

[Longchamp]

I think its a form of cyano or slime algae.

My roommate had something that looked exactly like what you describe. She dosed chemiclean and it went away, but it took a toll on her LPS (they just looked bad for a few days, one torch turned kind of white, but nothing died)


Edit: I advise against doing this... unless its killing your corals. What i'd recommend is just doing small partial water changes and getting some phosphate removal media. Suck out the brown algae when you do the water changes.