Yellow Out Swimming Pool Chlorine Shock Enhancing Treatment - 2 x 4 lbs. Used in conjunction with pool shock to safely remove green, yellow, brown, and pink algae from your pool Simple to use, requires no brushing, and cleans up algae gently without the use of harsh chemicals Safe, non-toxic and can be used on all pool surfaces, including vinyl liners Compatible with pools operating a chlorine generator Dosage: 2 lbs per 15,000 gallons, Quantity: 2 x 4 lb. Bottles