What impact does chlorine have on pH levels?

Chlorine is a commonly used disinfectant in pool water, and it can influence the water's pH levels through a couple of different reactions. When chlorine is introduced into water, it can form hypochlorous acid, which is a weak acid that can temporarily lower the pH. However, the primary effect of adding chlorine, especially when using forms like calcium hypochlorite or sodium hypochlorite, is to increase the pH levels of the water.

Calcium hypochlorite, for example, has a high pH (around 12.5), and when added to the pool water, it can cause the overall pH level to rise. Chlorine’s chemical interactions in the water often lead to a net increase in pH, especially when chlorine is added in larger doses or in a pool that has a low total alkalinity. This is why it is important for pool operators to monitor and adjust pH levels regularly after chlorine additions to maintain optimal water balance.