Poly aluminium chloride (PAC) is a kind of inorganic macromolecule flocculant. Through the hydroxyl ion bridging function and the polyvalent anion polymeric function, it produces large molecular and high electricity inorganic macromolecule. It adapts a wide PH range of 5.0~9.0, and the best is between 6.5~7.6. Add water to the product to dilute into a 10%-20% water solution(calculated by weight). Then find the best dosage through experiments according to water quality and purpose.