A method and composition for reducing chemical oxygen demand is presented. The composition includes a sulfate free radical precursor and a transition metal catalyst in contact with the sulfate free radical precursor. When the composition comes into contact with water, the transition metal catalyst reacts with the sulfate free radical precursor and produces sulfate free radicals in the water. The composition produces sulfate free radicals which reduce chemical oxygen demand in the water of aquatic facilities. The composition is provided in the form of a powder, granules (coated or uncoated), or an agglomerate.