The Stain Drop All Purpose XpH is a highly effective stain remover that will function in a wide range of pH and chlorine levels. Many stain removers needs to have certain conditions met for the stain remover to work, but the All Purpose XpH will work in all conditions. It is compatible with all pool surfaces and sanitizing systems. This product can be used with Stain Drop #1, #2, and #3 to effectively remove stubborn stains and scale from pool surfaces.