An important parameter in the maintenance of your swimming pool is the pH value of the water in the swimming pool.

Among other things, the pH value affects the effectiveness of the used disinfectant, in most cases chlorine.
Since the form of chlorine present is pH-dependent, the pH should be balanced at an appropriate level to maximize sanitizing effectiveness and ensure swimmer comfort.

After the addition to water, chlorine creates hypochlorous acid (HOCl) which dissociates into hypochlorite ions (OCl–).

HOCl is the form of chlorine, which, compared to OCl–, acts as a stronger disinfectant. To ensure that the added chlorine effectively disinfects the pool water, the pH of the water must be taken into account.
Around pH 7.5, HOCl and OCl– are present in relatively equal amounts. Below pH 7.5, the equilibrium shifts to favor HOCl; above pH 7.5, the equilibrium shifts to favor OCl–.

Ideal pH levels are typically between 7.2 and 7.6; pH levels above this greatly reduce the effectiveness of chlorine sanitizers, and pH levels below this can cause skin and eye irritation.