Calcium hardness

Calcium hardness is a measure of the dissolved calcium in water, commonly reported in parts per million as calcium carbonate. Total hardness is a broader measurement that also includes magnesium. Check which measurement your test strip or kit provides: a pad labelled “total hardness” is not measuring calcium alone. Neither result is the same as pH or total alkalinity.

The recommended calcium hardness range depends on the spa and its water-care system. Excess calcium can contribute to scale, while a reading below the specified range also needs attention. Use the requirements for your own equipment when assessing a result, rather than copying another model’s target. Legacy Spas lists calcium hardness among its showroom water tests; bring your test-kit details if you need help comparing readings.