Higher Calcium Numbers Seem to Control PH better

[CarlD]

Hard-sided pool or vinyl? If it's concrete or shotcrete or gunite or tile or plaster it makes sense. You keep calcium in your water to keep it from leaching out of the walls. When it leaches out, it increases the calcium in the water and that is alkaline. So if your water has calcium in it, it cannot leach out and your pH stays where you put it.