Calcium Chloride

Also Known As:

Soft water does not contain enough calcium. In household water, this can translate to a strong smell and taste, but in a pool, soft water can cause surface pitting. Adding calcium chloride can combat this problem.

Calcium chloride is a white salt used to raise the calcium or total hardness level in a pool or spa. (Other applications include melting ice and snow, as an accelerant in concrete and as an additive in fire extinguishers.) The compound is solid at room temperature, usually in a granulated or flake form, and dissolves easily in water.

For a masonry finished pool, the calcium hardness should be 150 to 200 ppm (parts per million). For a vinyl-lined pool, the levels should be between 80 and 150 ppm. Calcium hardness should be checked monthly. Poolside kits are available, as well as computer analysis via a pool services company or retailer. Test strips offer limited results, while drop tests offer the true calcium concentration in 10 ppm increments.

If the water is too soft, calcium chloride can be added in three parts, circulating for at least four hours between each part. The water should then be retested and the process repeated if necessary. If too much calcium chloride is added, the water can be diluted by adding more to the pool. Contact a pool professional for more information.