Keep the swimming pool ready with Clorox Pool&Spa Chlorinating Tablets. They kill bacteria and stop algae. Each tablet is stabilized to ensure protection from algae and bacteria. They're also protected from sunlight, enabling them to last for a longer period of time. Use these Clorox chlorine tablets weekly for a good, clean swim you, your family and your friends can enjoy. For use in your pool's skimmer, feeder or floater. These tablets are composed of 99% chlorine, making it arguably the strongest chlorine tablet on the market. Make sure you pair this 3in chlorine tablet with a quality shock, such as Clorox Pool&Spa Shock XtraBlue2.