Red or Brown algae/bacteria problem please help
I'm fairly new to saltwater aquariums and recently purchased a 75g saltwater aquarium off of a guy i work with. This guy just completly ignored this tank and everything in it. Getting to the point the tank has about 60-70lbs of live rock and ive had the tank setup now for alil over a month and when i got the tank the rocks where pretty bare(no coraline algae etc) and now its a redish looking brown substance covering the rock and the coraline algae that had begun to take off. All my water paramaters are good execpt the nitrates are around 20ppm. The tanks runs 2 rena xp2 canisters and a penguin bio wheel 350. I also have 2 powerheads at opposite ends. Tank inhabitants are percula clownfish,blue hippo tank,teardrop butterfly,chocolate chip starfish, and a scarlet cleaner shrimp and 5 turbo snails and some small crabs. Ill post up some pics and if someone could help me identify the algae/bacteria i would appreciate it. It really doest look like "red slime" algae. It has a brown and redish color to it and im also seeing some green algae.