Changing the pH
Increasing or decreasing the pH may also be used for disinfections of water. The pH can be increased by adding lye, or decreased by adding some kind of acid. This is unsatisfactory, however, because the pH has to be normalized again whether the water is going to be used on the fish farm or whether it is the outlet water sent to the recipient. This method is sometimes used for treatment of purified process water and bleeding water from slaughter houses.