New PROtech DY-Chlor II 56% Swimming Pool Chlorine Granules 50 lbs New PROtech DY-CHLOR II 56% Chlorine for Swimming Pools Self stabilized - Dy-Chlor II has a built in stabilizer containing cyanuric acid, which helps prevent sunlight from degrading the chlorine. Works continually to kill bacteria - The available chlorine (56%) is released when the product is dissolved in water and works continually to kill bacteria, control algae and destroy the organic contaminants in water. Gentle on pool equipment and surfaces.