CH- Calcium Hardness

  • (CH) Calcium hardness indicates the amount of calcium in the water.
  • Over time, water with low calcium levels will tend to dissolve calcium out of plaster, pebble, tile, stone, concrete, and to some extent fiberglass surfaces.
  • Keeping the water saturated with calcium will protect pool surfaces from premature failure.
  • A plaster pool should have CH levels between 250 and 350.
  • Total hardness is the sum of calcium hardness and magnesium hardness.
  • Most test strips report TH instead of CH causing plaster degradation from low calcium.
  • To increase your CH level you can add calcium chloride.
  • Cal-hypo will also increase CH levels, for every 10ppm of free chlorine added to your pool you increase your CH by 7ppm.
  • To decrease you must remove water.