Quote Originally Posted by jimsflies View Post
Check everything real well. Make sure no missing livestock and that pumps, temp, etc. are where they are supposed to be. Test the water.

How do corals and fish look?
+1 double check everything.
Sounds like a bacterial bloom but with out a pic its hard to say. If it is a bacterial bloom make sure you have adaquate surface movement to get oxygen in there. Bacterial bloooms are usually not fatal to inhabitants if handled properly ie keeping oxygen levels up.