I've had my tank for eight years and have had my fair share of mistakes.I have moved alot with different typest of waters and still I'm getting green algae.I keep my light on no more than six hours.Let me start off with I have a 75 gal comments tank with one shrimp and six small fish.I feed them a half cube of mysis shrimp once a day.My tests are always great.I also have a octopus skimmer.I'm also adding stuff for metals etc.I do a 10% water change every two weeks.