Pool maintenance is as simple as can be with Pool Frog's ultimate delivery of hassle-free Fresh Mineral Water system. The Pool Frog Bac Pacs come pre-filled with chlorine and easily insert into the Mineral Reservoir dispensing low levels of chlorine for 1-3 weeks. With precise feeding, you will use up to 50% less chlorine. The handles on the Bac Pac are easy to remove and you will never have to touch messy chemicals again.