SeaKlear® 90572SKR 2 lbs Metal Stain Remover. Metal Stain Remover works effectively to remove stains caused by excess metals in pool water. This special formula is effective for the removal of iron, copper and manganese staining. These may appear as brown, grey, turquoise or black stains. Metal Stain Remover should be used first if stains are already present. For metal stain control and prevention use weekly.