The Natural Chemistry Pro Series Stain and Scale helps protect pool surfaces and equipment from the effects of stain and scale buildups caused by: excessive calcium, iron, copper, and other minerals. This product does not add phosphates or harsh acids. The Pro Series Stain and Scale helps reduce scale from forming on chlorine generator and UV crystal lens to help them perform at the best rate possible. This product can be used with most sanitizing systems besides biguanides, and is compatible with all pool surfaces. Professional stain and scale remover Targets calcium, copper, iron, and other minerals Works with most sanitizing systems except biguanides