Drilled it so half of the side fits the canisters, other side houses the sump. I just wanted to overfilter the tank, but overlooked the maintenance of the canistersThere is a reason I got rid of my fx5 and went with 3 ac110s. I hated cleaning that thing and I had only one to clean, can't imagine 3. Didn't you drill your tank and go with a sump? Why bother with canisters?