it looks dark green/brownish.
i've had my tank set up for about 1.5 month, 35gallon tank, 2 powerheads, backpack skimmer, about 20 lb of live rock 2 peppermint shrimp and 9 snails. all is alive still but this stuff scares me and it keeps on growing. i'll do some tests on my water and post a pic later tonight.
thanks