A method of reducing a dissolved metal concentration in a body of water, the body of water containing phosphorus, the method comprising applying a product to a body of water, the product including at least one trivalent metal salt and at least one additive,
- binding the phosphorus that is present in the body of water with the at least one trivalent metal salt, the at least one trivalent metal salt including a trivalent metal salt of lanthanum and/or cerium, at least some of the trivalent metal salt dissolving within the water to release dissolved metals;
- and
- binding the dissolved metals with the at least one additive, the at least one additive including magnesium oxide.