If you do not clean the canister filter on a regular basis (weekly), nitrates will start to build up in your tank. I used to run a canister filter on my old tank and had nitrate problems constantly. Removing the canister filter cut my nitrates in half.
Any mechanical or chemical media allowed to become a biological filter will produce nitrate.So both filter floss,carbon,sponge filters etc. can become nitrate factories.
I used to have to crapister filters on my 90 they were rated for way more then the tank size. After years of battling nitrate problems I built a refugium with a better skimmer and no nitrates at all anymore. Look on youtube at the protien skimmers and you will see the hype. I would forget the canister and get the best skimmer you can afford. The power sweeps are junk too by the way.