SeaKlear Stain Prevention & Remover, 1 Quart Bottle Effective for metallic stain removal and prevention Prevents hard water scaling Best performance on the market Ideal for vinyl, fiberglass, and plaster pools Used for metallic stain removal and prevention and hard water scaling Use when starting up a plaster pool; controls plaster dust Most effective metal stain prevention and removal product available Prevents and removes stains and scale in vinyl, fiberglass and plaster pools Made in the United States