Forza Replacement filters fit the Rena OEM Forza 15-25gal Forza Power
Filter. Slide into the slot on the filter for easy filter change. The
filters feature all three recommended filter types Carbon (chemical),
White (particulate/biological) and a plastic grill which removes larger
particles. Depending on the aquarium load change the filter every 1-2
months. They can also be rinsed out in water from the aquarium in
between changes. See filter directions for further details.