New 66 gal set-up/Brown Alge


New member
Last Wednesday I set up a new 66 gallon tank with live rock from Tampa Bay Salt water. The lighting on the tank is supplied by 235 watts of T5 10,000 K and atinic bulbs.

Over the last couple of day I have noticed all of the new rocks being covered by brown alge; it is even covering the few sponges that were on the new rock.

There is about 1/2 dozen snails and 1/2 dozen blue hermit crabs in the tank which are on the rocks but haven't been able to rid the rocks of the brown alge.

1st question: I thought most alge problems were green on new rocks and secondly, why the brown alge covering the new rocks and now some of the substrate. I have also shut off the light now. The rock was getting about 9 hours per day and then moon lighting for the rest of the day.

Any suggestions; thank you!


New member
Is the brown algae powerdery? Likely it's daitoms - a normal part of a new tank cycle. Leave them be, they'll go away on their own.
Your tank will go through a number of different colors. With my experience, brown comes first, followed by green, then you'll get the red slime, then it'll almost disappear entirely.