Hi Ive only used Hang On Filters but have read canisters are way better I just dont know how they work. I was wonderin if anyone could explain this to me also Ive seen several aquariums with overflow systems built into them already with the holes drilled n everything is this needed for a canister filter??? Can someone show some good pics how everything is conected and how it looks in the aquarium Ive seen so many pics of diff filters but have no idea how the plumbin work or how its conected. Thanks in advance.