I have 2 aqueons on my 26g Bowfront and they are great. In regards to bio filtration, they have tons of space for that too right in the filter with the biogrid difuser and the filter cartridge holder itself. They never have to be replaced nor rinsed for that matter unlike the aquaclear media or any other media for that matter. The only thing you replace monthly or whenever its needed is the filter cartidge. You just pull it out and put the new one in. DONE! all while the filter is still running. Also the Aqeuons can start running dry, meaning no priming neccesary, like the aquaclears or some other filters. Mine are real quiet as well. I have petrified rock and driftwood in my tank and the water CRYSTAL CLEAR. Trust me you will be happy with the Aqeuon. Mines running 2 plus years now. Good Luck!