Every day i have this brown film over the top of my rocks and i rub it off every day with a tooth brush. I dont know what else to do. A month ago i had really bad hair algae i did let my maintenance routine go a little but been fighting like hell to get the tank back on track so idk if its just hair algae trying to come back or something else. My po4 is .00-.02 (checked with hanna checker), my no3 is 12 (checked with NYOS). Tank has been up and running for almost 2 years now.