i just got my 1st canester this week so im far from the best person to give advice..BUT the fluval 305 might be worth you looking at. its got 4 good size pre pads that act as bio as well as taking out bit dirt, then it has 3 trays split in 2 nothing stoping you puting fine pads in all of them but i dont think u would have to,,,i had a look at mine for the 1st time today its catchin all that its sucking up, i swaped it around a bit tho fine filter last was wrong even tho thats what the guy in shop told me i think in time i might just hav fine in 1 side and put more bio in..