I will not trust placing a canister filters in my living area because it is an unsafe system for two reasons. First, if it leaks, it can drain the tank and flood the the floor. There are O rings and clamps in canisters vulnerable to failure by human mistake or wear and tear. Second, it is a closed system not open to the atmostphere. A dirty canister in a power outage can quickly turn aerobic and when the power returns, it can flush out toxic gases to wipe out the fish. Canisters are marketed for having large media volume. True, but not open to the atmosphere means that it subtracts from, rather than add oxygen to, the flow through. In contrast, Sponge filters, HOBs and sump systems are open systems you never have to worry about going anerobic.
Hobbyists tend to believe that the more sophisticated systerm they buy, the better for the fish. Not true. Sponge filters work perfectly fine and are the the most economical and commonly used system for multiple fish room tanks when appearance doesn't matter. HOBs, are simple and inexpensive systems that can be used for small to big tanks, but need frequent media change because of the small capacity. Sump systems should be reserved for the biggest tanks which offer high flow rate and the largest media volume, but it requires brain to set up the more complicated plumbing system.
