Brown spots on live rock?

Mbarratt · Dec 13, 2015

I have recently been noticing these brown spots over my live rocks. It seems to be spreading. Can anyone identify what it is and how to stop it.

ThRoewer · Dec 14, 2015

It could be an algae, but it's hard to be sure without a clearer close-up.

Dmorty217 · Dec 14, 2015

Algae of some sort. Caused by excess nutrients more than likely.

ca1ore · Dec 14, 2015

Either algae or sponge.

CoralsAddiction · Dec 14, 2015

Is that a recent setup? Live rock looks fairly new. Could be diatoms.

Breakthecycle2 · Dec 14, 2015

Looks like sponge growth to me.

A1t2o · Dec 14, 2015

If it grew slowly then it is probably a sponge, but if it grew quickly then it is algae.

Mbarratt · Dec 14, 2015

My tank has been up for roughly 4-5 months. Is sponge growth bad? What should I do to clean it? Or should I leave it?

Dmorty217 · Dec 14, 2015

Sponge is good! I would leave it either way. Your CUC will take care of the algae