I'm planning on replacing my 125G with a 240G and I don't want to use canister filters on the main tank. I was hoping to have a 45 - 60G for the sump, the top of the main tank to the bottom of the sump is roughly 5 feet. The reason I haven't set up a sump yet is because I don't understand them and I'm not going to take on a project I don't understand. I do NOT want to drill any holes into my tanks, I was hoping to maybe have an external overflow but even still these are things I know nothing about. I would like to know what size tank i should use for the sump, what size pump should I use for the return, what materials would I need and how would I plumb it? I figure there's no better place in the world to ask these questions than here, thank you very much for your time.