Lowers the PH value (acidity) of your pond water. Recommended dosage of PH-: 25 ml PH- will lower the acidity of 500 liters water by 1 PH (1 liter for 20.000 liter pond water). Based on the volume of your pond, the required amount of PHshould then be dissolved in water in a watering can and poured over the surface of the water, avoiding contact with the pond plants as much as possible. The PH value of your pond water should never be lowered by more than 1 PH per 24-hour period. This can be checked by measuring the PH value of your pond water before and after each recommended dosage. Special note: As reducing the PH value also lowers the KH value (carbonate hardness), the KH value must be carefully checked. If the KH value of your pond water is lower than 3°dH, you should not use PH-. In that case, first increase the KH value with KH+.