Total Hardness

Total Hardness (TH) is a measure of the concentration of dissolved minerals, mainly calcium and magnesium, in spa water. These minerals can come from a variety of sources, such as the spa water source, chemicals added to the water, and debris introduced into the spa.

Maintaining proper hardness levels is especially important in the spa industry because spas operate at higher temperatures, which can accelerate the negative effects of imbalanced hardness. Low hardness can lead to corrosive water that damages metal components, heaters, and pumps, while high hardness increases the risk of scaling on heating elements, jets, and spa surfaces, reducing efficiency and leading to costly repairs.

The ideal range for TH in a spa is between 200 and 400 ppm. If the TH is too low, the water can be corrosive and can damage spa equipment and surfaces. If the TH is too high, the water can become cloudy and cause scaling on spa surfaces.

To adjust the TH level, spa owners can use chemicals such as calcium chloride to increase the TH level, or chelating agents to reduce it. It is important to test the TH level of the spa water monthly and make adjustments as necessary to maintain proper water balance and prevent damage to spa equipment and surfaces.