brown on rocks and powerheads.
 

in my tank, my rocks are starting to turn brown and getting some brown on my powerheads. is this okay though? what is it.

It is all fine. It is most likely diatoms and just part of the cycle. Although can be due to high phosphate's as we'll.
Do you use ro water or tap water.
Otherwise it means your tank is doing what it should be.

corals
 

this will not harm things in the tank right? like fish and coral

it shouldn't however if it's brown slime on your corals you have another problem.

I think this tank is doing it's initial cycle as discovered in this thread:
http://www.canreef.com/vbulletin/showthread.php?t=46809

Yes your corals and fish could be in peril if your tank is cycling.

It all depends... were you sleep dumping in the tank? ahah

tap water
 

using tap water. priming it and letting it sit.

should i be using ro water? will it make a difference if I start using r/o water now.