Interpet pH Adjuster for Akaline Ponds - for lowering high pH pond water from alkaline to neutral. Alkaline pond water (pH 7.0 - 14) can be caused by using cement around the pond that drops into the water or calcium rich rock around the edge of your pond. Once this gets above pH 8 it needs reducing to keep the pond water safe. This easy to use product adjusts the pH to keep it in the \"safe range\" for a pond between 6.5 and 8.0. (pH must be stable within this range).