I'm thinking of replacing my Marineland C530 Canister filter with another AC110 to make two AC110's. Canisters for the most part are highly over-rated IMHO. The AC110 does just as good even though it's HOB. I never understood the resentment towards HOB filters. Even with a canister filter you still have an intake/outtake hanging on the back. The difference is you don't have a heavy container you have to lug around every time you do maintenance. With AC filters it's so easy to squeeze sponge and put back and the biological works just as good as a canister. The water agitation on top is better for the fish too. I recommend AC110, plan on having them on all my tanks and do away with canisters for good.