The key to maintaining a crystal clear pool is a steady routine of sanitization. Regal® sanitizers are designed to kill bacteria and algae. Regal® Sanitizers have built-in protection from the sun to maximize chlorine life. 3-inch slow dissolving chlorinating tablets with 90% available chlorine which kills bacteria, destroys organic contaminates and controls algae. For use in automatic chlorinators, floaters, and skimmers.