Stain Drop All Purpose XpH is a powerful product formulated to prevent and assist in removing stains and scale caused by metals and minerals. Include it in your pool opening or start-up for a stain-free season! Stain Drop All Purpose XpH works great in wide pH and chlorine ranges. Great for off-season prevention. Highly chlorine tolerant, and low pH tolerant. Proven technology is effective in removing light stains & scale. When used according to directions, this product is safe and compatible with all pool surfaces and sanitizing systems, including salt pools.