i have a 5'x2'x18" acrylic tank, i believe it is clarity plus. it has a center overflow and 2 large openings centered on the top. i'm using a wet/dry with 40l as the sump, and the back of the tank is drilled in 2 places up near the top for the returns from the sump. i'd like to add an aquaclear, or at least a canister filter, but there are no smaller openings cut out on the top for even the canister intakes/outputs, much less hanging an aquaclear. is it possible to cut/drill openings in the top of the tank without completely emptying the tank? what i'm thinking is to just drop the water level down a few inches and hold something under the cuts to catch the falling debris . . .