I've got an establishied 46 gallon tank that's 2 years old. I've been using an HOB filter(marine biowheel 400) and i'm wondering if a canister wouldn't do a better job. I know most people here prefers sumps but my tank isn't drilled and I'm worried about flooding everywhere. Besides the plumbing would be way over my head. Can someone teach me about canister filters? I have no idea how they work, what maintenance do they require? I've been looking at the new Fluval series G which is expensive. Do people think I should switch to the canister or should i just keep the HOB? I've been having a green hair algae i keep on top of .