Pristine Blue MetalShieldThe Pristine Blue MetalShield product is a liquid formula that is regularly used to prevent and fight against metal staining and scaling in pools. This stain fighter is effective on all types of metals including copper, iron, magnesium, and calcium. MetalShield is compatible with all types of standard pool systems, including chlorine, bromine, and salt. This stain and scale remover is also compatible with all types of pool surfaces. Easy to use liquid