Brown algae!!!!!

one month ago I started a 10 gallon reef tank. I have 10lbs of live rock and 1 inch of live sand, one powerhead, external filter. I had two powerheads but it made the temp too high 80F.
My ammonia level never registered or my nitrite level. Nitrate is about 5ppm.
Now I have a major algea problem, brown algae everywhere.
Bought one turbo snail and one hermit crab.
the hermit crab is barely moving.
What am I doing wrong??

 

The brown algae is diatoms. Perfectly normal right after the cycle. It will use up the available silicates then start to fade away. Hermits wont do much, but most snails will eat it.

 

how about water change? I have never done one?

 

The silicates could be coming in in your water if it is tap water so Im not sure if a water change could help.

 

For example I added matrix to my canister filter the other week. After reading this thread I just realized that the brown algae bloom is probably from adding the new media into the filter. Give it time, it goes away.