My opinion will be on flow is the same as the others. 55 gallon tank…I would consider getting 3 Korilia #3’s for water flow. You want to keep detritus material in the water column by keeping the water constantly stirred. So that the skimmer can get to it. Settling in the sand over time just becomes a problem later. Cyano cough cough..been there..and don’t wana do that again.
As for the Canisters there are mixed opinions. And mine being against them period. They trap that detritus material inside…so they decay and add more Nitrates into your system. The purpose of us skimming is to remove those DOC’s so they don’t do that. Lowering the amount of nitrate build up. Sure you may get others who say just clean that more often. I still think its not enough. And on an old tank…cleaning my fluval 205’s x2 every 3-4 days got VERY old fast. Ill spare you the story but after removing them did my nitrates finally start to fall during that crisis I had. And I am one of those hard headed people who learn the hard way. So its only my opinion but I think you are better off with depending on LR Skimmer and weekly water changes.. vs that canister filter for cleaning that water.
Tunez and Korilia I am fond of for power heads if you are looking at some. Try them out for size.
PS. Remember the ocean current is strong…I very much doubt we can reproduce it…but a lot of flow is never a bad thing in my personal opinion. Ask a diver what its like by a reef…=) terbulant.