Flippin’ FROG adds minerals and a small amount of chlorine in an easy-to-use dual cartridge system. How does it work? Flippin’ FROG uses minerals to destroy bacteria so you don't have to use so much chlorine, which saves you money. This results in water that is soft and silky, and won't bleach out your swimsuit or create smelly odors. Flippin' FROG flips over to let you know the chlorine is empty and needs to be replaced. Just replace the bottom chlorine cartridge, and never worry about touching or pre-measuring chlorine again ! The green mineral cartridge lasts 6 months or one pool season - whichever is shorter - while the chlorine cartridge lasts about 3-4 weeks. Flippin' FROG is great for pools 12-18 feet in diameter or 2,000 to 5,000 gallons.