Canister over time gets really dirty. If you are going to use one you neeed to completly rip it apart and 100% clean it at least once a month. in a fish only tank i would suggest a small cheap skimmer. and a powerhead to help move a little water.
man i just got my fuge and it is the best thing in the world. after 1 day of hooking it up i swear i already see life in the fuge. I am taking down my dads canister filters and ordering another fuge for his 75. i still say get a refugium
or if you want, keep the canister filter and get an Hagen aqua clear 70 HOB and mod it into a mini fuge. My buddy made a mini fuge out of this but he never kept a canister filter. Search google for DIY aquaclear mini fuge.