Easy to use – simply replace the old cartridge with a new one every two weeks Double insulated pump Air release valve for air trapped inside filter chamber Sediment flush falve at bottom of filter chamber. Minimum pool size (water capacity)- 4,000 gal (15.1m3). Maximum pool size (water capacity)- 15,200 gal (57.5m3) Works with 15-feet Easy Set, 15-feet Metal Frame, or 18-feet by 10-feet Oval Frame pools