Definition: Ammonia poisoning is a dangerous condition that occurs when free ammonia (NH3) is present in the water. At a level of 0.3 mg/l skin and nerve damage occurs. As the level rises, hemorrhages occur, striking the lungs first. Because ammonia can result in death very quickly, corrective steps should be taken immediately. Lowering the pH below 7 will provide some immediate relief, as will water changes and the use of chemicals that neutralize the free ammonia.