Stuff on my LR?

[urbanhellfire]

Iam going with a LR and a fish or two set-up. My LR and LS have been in the tank for Six weeks this friday. Iam starting to see some yummy green film algae on the rock so iam going to start adding a few snails, but I also have some very dark Black or very very dark Purple growth on the rock. Is this the norm?

Thanks everybody!