Ok the 4-5" of southdown has been in my tank with saltwater for a couple weeks now. The project got backed up due to a leak/flood which I posted about a couple weeks ago. So I put 2 powerheads temporarily in the show tank so I could keep the water moving so it wouldn't go bad. I haven't had any lights on over the tank yet. Today I noticed a light brown patch about the size of a quarter on my sand bed. It just looks as if the sand there is a different color. Like a rust or a copper color. What is it? Brown Algae? Excuse my ignorance but this is my first saltwater tank so all these things are new experiences to me
. Should I worry about it at all?