pH Down 16kgPH Down lowers the pH level of water by counteracting alkaline compounds. Lowers pH (increasing acidity) to the correct level required for the good health and longer life of your fish. Contains sodium biphosphate, which will not exacerbate algae. Use as required in small doses to avoid over adjustment. This will gradually decrease pH to optimum levels so as not to stress the fish. Do not overdose. To ensure ongoing pH stability, use an Aqua Pics KH