Brown algae?

[keithntracy]

This happened in a matter of 8 hours. It was not like this in the morning. All the rock turned brown and what you can't see in the pic, is there are a bunch of airbubbles on the rock. Any ideas? We started cycling last Friday.

 

[bertoni]

That's fairly normal for a new tank. I would ignore it. These blooms often or even usually go away on their own.

Now might be a good time to do some water changes, maybe 25% each, if you have the energy.