I just got an Eheim Classic 2217 for my 55G and it is awesome! I cannot believe I waited so long to get a canister. I definitely recommend it! I know you will have enough flow to be able to remove the powerhead , but I don't think it will be too much. Hopefully some more experienced Eheim owning members will chime in.
+1 on the rena , an xp3 will give you plenty of filtration and is an absolute work horse . You can pick them up from big Al's (this forums sponser) for less than $110 shipped if you use the coupon code.
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