Turn a Fountain Bowl into a biological filter with the new Fountain Bowl Biological Filter Kit. Using a Fountain Bowl as a biological filter is a great way to add filtration to any pond or waterfall with minimal effort and at an affordable price. Depending on the bowl size, these Fountain Bowl Biological Filters can filter up to 3,500 gallons (13 200 L). We offer biological filter kits for the round 32″ and 40″ Fountain Bowls and the square 27″ and 33″ Fountain Bowls. The kit includes (4) internal shelves, a custom filter mat, a bio-media net, a 1.5″ rubber bulkhead, a tee-fitting, and BioBalls Biological Filter Media.