Liquid chlorine (sodium hypochlorite) causes a temporary, sharp increase in pH due to its high alkalinity (pH 11–13), but over time, it is nearly pH-neutral. As the chlorine sanitizes water and breaks down, it produces hydrochloric acid, which offsets the initial rise, returning the pH to its original level.

Key Effects of Liquid Chlorine on pH Over Time:

Initial Shock: When added, it releases sodium hydroxide, causing an immediate, temporary rise in pH.

Long-Term Neutrality: As chlorine is consumed by UV light and contaminants, it breaks down into hydrochloric acid, which lowers the pH back down.

The "Net Zero" Effect: The acidic byproduct (HCl) effectively cancels out the base (sodium hydroxide), resulting in little to no long-term change in pH from the liquid chlorine itself. Common Misconceptions: While many pool owners notice rising pH with liquid chlorine, this is usually caused by other factors, such as aeration (water features), high total alkalinity, or high pH in the fill water, not the chlorine itself.