I have a 120 galon fish only tank with a moderate amount of fish...nothing very big. I was wondering how much filtration I should have. I currently have a sump system, a cpr backpac with a skimmer, and an emperor 400. I also have 2 powerheads ( 1 on each end of the tank). I want the water quality to be good but I notice alot of air bubbles in the water and some debris as well. I also have 44 gallon tank with an emperor 400 only and the water quality and clarity are much better.Any suggestions would be greatly appreciated.