brown algae

[teachin4alivin]

I have what seems to be brown, dark algae all over my rocks. its no where else it the tank. This is a 90g tank and has been running for about a year. water test good across the board. Any ideas

 

[ZR440]

Seriously, a lawnmower blenny will work wonders.

 

[teachin4alivin]

any idea of the cause of this? the live rock looks bad. I have a second 45g tank do all the same things and the rock looks great clean with life looking like it lives on it.