What can excessive sunlight exposure do to pool chemicals?

Excessive sunlight exposure can significantly deplete chlorine levels in pool water. When chlorine is exposed to UV rays from the sun, it starts to break down and lose its effectiveness. This process is known as photodegradation. As a result, the sanitizer's ability to kill harmful bacteria and maintain safe water conditions diminishes. This is why it's common for pool operators to use stabilizers, such as cyanuric acid, which help protect chlorine from UV degradation by absorbing some of the sunlight and allowing chlorine to remain effective for a longer period.

The other options do not accurately reflect the effects of sunlight on pool chemicals. For example, sunlight does not increase calcium hardness; rather, it is primarily influenced by the source of the water and any added chemicals. Enhancing overall water quality or stabilizing pH levels is also not directly linked to excessive sunlight exposure, as these factors depend on the balancing of various chemicals and regular maintenance rather than the sun’s effect.