The measure of all the dissolved minerals such as calcium, magnesium and sodium is known as total hardness. Regarding pool water chemistry, it’s known as calcium hardness. High or low levels of calcium hardness can result in issues, so the recommended level for calcium hardness is 200 – 400 ppm. To find out the hardness of you swimming pool, you will need to perform a calcium hardness test.

You can increase the calcium hardness level by adding calcium chloride. If the swimming pool suffers low hardness due to the low quality of the fill water, calcium hypochlorite should be added. You can perform a calcium hardness test if you suspect insufficient levels.

High calcium hardness results in scale formation on the pool surfaces as well as scaling in the pipes, plumbing and filter. High calcium levels will also cause sore eyes of swimmers.

If the calcium is a result of pool chemicals, draining some or all of the pool water will lower the calcium hardness level. If the cause is the fill water, commercial hardness reducers or chelating agents will bond with the calcium to keep it trapped in solution.