Robelle 2550 Mineral Out Stain Remover for Swimming Pools, 1-Quart This product helps prevent discoloration of pool water due to iron, calcium, manganese, copper and other metals and minerals which may be present in the water supply This product is an excellent general purpose sequestrant which helps protect plumbing and pool walls from rust, stain and scale It should be used for all pool openings and closings and throughout the season as needed 1 quart per 10,000 gallons