Problem with canisters seems to be the trapping and holding of organics. Unless you clean them weekly you'll have algae issues do to excess organics. Lots of reefers like using filter socks in the sump to grab all the crap before it hits the sump and gunks up everything. I run a canister on my 75 gal fw and the thing is nasty after a month. I would never run one on my reef. You can achieve flow with a couple reasonably priced power heads. Get a skimmer and lr. Ditch the canisters, or run the smaller one with floss and clean it every few days. Again.. sump is 100% way to go imo