Swimming Pool Winterizing Winter Closing Kit 20,000 Gallons 20K Algacide/Shock New Winter Closing Kit up to 20,000 Gallons for swimming pools Includes 1 Quart 50% Algaecide - for control algae in swimming pools Includes 2 pounds Granular Chlorine Includes complete winterizing instructions For pools up to 20,000 Gallons