Sani Marc Summer Smiles 30-07335-12 1.2Kg Stain Out Metal and Stain Remover is a sequestrant that’s mainly used to remove stains caused by metals such as manganese, iron and copper from all types of pool liners. Stain Out solubilizes metals in water and also helps to correct water colored by these metals. Stain Out is used in combination with Metal Out to completely remove metals once they have solubilized in water.