GLB 4 lb 3" Stabilized Chlorine Tablets (90% Available Chlorine) GLB Large 3" Tablets use these slow-dissolving tablets for continuous disinfection with floaters, feeders or skimmers.  ACTIVE INGREDIENTS:. Trichloro-s-Triazinetrione : 99%. OTHER INGREDIENTS : 1%. TOTAL : 100%. Available Chlorine : 90% DIRECTIONS: It is a violation of Federal law to use this product in a manner inconsistent with its labeling. Reentry into treated swimming pool is prohibited above levels of 4 parts per million (ppm) available chlorine.