Helps remove stubborn metal-based stains from all types of pools. Especially effective on fiberglass pools. Stain Wipe is an ascorbic acid alternative that provides strong stain removal properties for swimming pool surfaces. Stain Wipe can remove metallic and some organic-related stains. However, because Stain Wipe creates a problematic chlorine demand, it should only be used when other stain removal products have failed. Some stains cannot be removed without draining the pool.