Yeah I think with the overflow you should go with a sump, you could use 30 gallon totes you get from walmart for a hell of a lot cheaper than a 55 gallon tank, I am a firm believer in sponge filters and believe every tank should have one so I think it would be beneficial for you to add one into your tank too to supplement your other filtration. I think the idea of having the overflow pipes lead to a canister filter, some good brands are Fluval, Eheim, Polar Aurora, or you can make your own
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