I have a friend that asked me a question about brown algae. He has a 75 gal
Discus tank. He keeps it slightly acidic. The lights stay on about 8 hrs a day , but the tank also gets some sunlight. What causes brown algae and what can be done to correct problem? I don't know every detail of the tank. He uses a canister filter, but I don't know what is put in filter. I just need general things to look for to help him get rid of the algae. Thanks!