I have the Marineland Canister filter, love it! The carbon bags are convenient and easy to rinse and use; however, unlike the polishing pads, they don't fit neatly into the trays. Even if you can flatten out the bags as much as possible, it leaves too much room for water to bypass. I prefer using Marineland bulk carbon and bagging them in nylon pantyhose, then it can be custom fit to the tray.