Sequa-Sol holds iron, manganese, copper and calcium in solution so these minerals do not react with other elements in the water. Use Sequa-Sol to prevent staining of pool surfaces or developing scale and rust on pool equipment, pipes and fittings. Sequa-Sol is a fast-acting sequestering agent that prevents staining, scale, and rust on pool equipment, pipes and fittings. This liquid formula holds iron, manganese, copper, and calcium in solution so these minerals do not react with other elements in the water.