The bio filtration capacity of a canister is much better than hang-on type, because it forces water to go through filter media more evenly. Also there is no limit on how large a canister for a tank, but the size of hang-on filter is limited to how much space is available on top of your tank. Hang-on type has a much better mechanical filtration capacity because its high flow rate, and ease of cleaning.
Not to mention that with a canister, you can place the inflow and outflow anywhere you want, its somewhat very convenient if you have a very large tank.
|