Low calcium hardness is an easy fix. High calcium takes patience.

Low calcium hardness is an easy fix. High calcium takes patience.

For low hardness, just add calcium chloride (the stuff they sell as “hardness increaser”). Follow the label, brush the pool, and test again in 24 hours. Done.

For high hardness, you have to dilute. There’s no chemical that safely removes calcium from pool water — sequestrants only prevent scaling, they don’t lower the number. So you drain some water and refill with fresh. How much depends on how high you are and what your fill water’s hardness is. Test that first.

The real annoyance? If your fill water is naturally hard (common in desert areas), you’ll always be fighting high hardness. Routine partial drains become a seasonal chore.

Don’t ignore either one. Low calcium eats plaster and grout. High calcium clouds water and leaves white crust on everything. Neither is a panic, but both need a response.