Coral Seas YO-4# Yellow Out Swimming Pool Chlorine Shock Enhancing Treatment, 4 lb 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