- slow-dissolving, tableted or granular, stabilized organic chlorine compound providing 90 percent available chlorine
- used for regular chlorination but must be dispensed using a floating feeder or an in-line feeder (chlorinator)
- contains an ingredient (cyanuric acid or stabilizer) that prevents the chlorine from being destroyed by the ultraviolet (UV) rays of the sun
- pH of 2.8, and regular trichlor tabs should not be placed in the skimmer, as the low pH will corrode the metal components in the equipment
