US Patent 7309444 Layered tablet water treatment compositions and method of use

The present invention relates generally to novel water treatment compositions. More particularly, the invention relates to solid water treatment compositions in the form of a water soluble tablet containing at least one halogen source and at least a pH compensating source in a layered tablet in which each of layer is configured to be simultaneously exposed to the water being treated and wherein one layer comprises the halogen source and another layer comprises a pH compensating source. Methods for controlling water biofouling and disinfecting water systems, particularly swimming pools and spas, are disclosed.