BioGuard Spot Kill - 2 Lb BioGuard Spot Kill - 2lb Fast acting granular algae killer For use in vinyl, painted, fiberglass or colored plaster surface swimming pools Use 2 pounds of BioGuard Spot Kill per 10,000 gallons of swimming pool water - for medium to heavy algae growth. 99% Sodium-Dichloro-s-trianzinetrione dihydrate