While I agree with upgrading to a sump , I also understand being on a budget, and at least to my knowledge, you would find it out of your current budget. You certainly can run a FOWLR tank with a canister filter with the right medium and maintenance. Also, you should make sure that the media isn't overstuffed in the trays in the canister, causing it to not seal correctly. You also need to make sure that 3ach of the O rings are in place between each tray and that the trays are seated against each other correctly. I found that placing my finger into the next tray tube as I stacked them allowed me to guide the trays together correctly, then repeat for the next tray. If any of that is out of whack, it will not seal properly. I'm assuming it is leaking from from where the motor head meets the canister body. As others mentioned, it could be that the main O ring is faulty or not in place correctly. If it has a Nick in it, it will leak. Also, while I used these for African Cichlids, I would use a silicon lubricant on that other ring lightly after cleaning it. I hope one of these is your problem, as they are simple fixes.