I'm hoping someone could help me. I don't know what this brown stuff that's growing on my powerheads and I'm seeing signs of it on rocks. Is this an algae, bacteria, fungus or something? How do I get rid of it? I'm currently doing lights out for 3 days - this is the 2nd day. I've seen some improvement but it's still massive. Also, I did measure my params and they are all good: Ammonia = 0, Nitrites = 0, Nitrates = 0, Phosphates = 0, Calcium = 400, Alk = 9. I have a 40 gallon breeder, T5 lighting, chaeto, GFO/Carbon reactor. It maybe that my params are good because these are eating all the nutrients from the water. Thanks.