a canister is just a different sort of filter, in this case will usually sit under the tank, so the only equipment actually on the tank are a couple of hoses to handle moving of water to and from the filter.
cloudy water, can be bacterial, if it's free floating in the water, it will clear up by itself but the problem with avoiding water changes is the ammonia and nitrite.
If you use city water, and do daily water changes, using something like prime that will condition the water and bind the ammonia should be very helpful to prevent problems with the fish.
as noted above, if you have well water, and don't need to treat for chlorine/chloramine ammo-lock