SpaGuard Rapid-Dissolve Chlorinating Tabs are small, fast-dissolving chlorine tabs designed for sanitizing and oxidizing spa and hot tub water, featuring effervescing technology for quick dispersal and reduced chemical guesswork. Each 1-inch tab typically treats up to 600 gallons of water, administering 3-5 ppm of free chlorine. To use, drop a tab directly into the filter compartment with the pump and jets running, allow it to fully dissolve, and wait until the free chlorine level is 1-3 ppm before re-entering the spa.