Speaking from experience......you will have nitrate accumulation and they are a pain in the a$$ to clean out. I had a canister on my 27G filled with LR rubble and carbon and still had problems.
Now run a 72G with sump and skimmer and LOVE it! Much easier by comparison. If you have anyway of running a sump, do it.
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Red Coral Online Store 
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45 Gallon Cube with 10 Gallon Sump, Lighting 8 bulb T5, Vertex IN 80 Skimmer
-2 Occelaris Clowns, Engineer Goby, RBTA, Peppermint Shrimp
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