We've got a FLUVAL 305 for our 80 gal. tank, but it is NOT meant to be used as your only source of filtration. We use it in addition to our sump, with a few modifications to the filter media. Once a month clean out the compartments, rinse the filter media, and replace the polishing pads. We replaced our nitrogen removal media with Chemipure packets (an all-in-one pack) which is working out great. For phosphate removal (if you don't have a reactor) you can get phosphate removing filter pads and use them in addition to the polishing pads.