The best store bought filter systems? check out Discount hydro.com; HTGsupply.com, stealth hydro.com. I actually go to the aquarium store and buy charcoal filter mesh sheets and hang it over the intake on the ac in my growroom. After about 20 days, I take it off and replace it with new and then pu the old one in my fish tank to absorb ammonia. After a few days myfish start swimming upside down....Just kidding on the fish. They usually just lay around and get the munchies.