Chlorine in pool water is used to not only kill germs, but also to:

Chlorine plays an essential role in pool maintenance beyond its well-known function of disinfecting water. One of its key additional functions is to oxidize organic matter. This process occurs when chlorine reacts with contaminants like leaves, dirt, sweat, and oils introduced into the pool by swimmers. Through oxidation, chlorine breaks down these organic materials into simpler, less harmful compounds, thus keeping the water clearer and more pleasant for swimmers. This reaction is critical because allowing organic matter to accumulate can lead to water quality issues, making regular chlorination a vital part of maintaining a safe and inviting swimming environment.

The other choices do not accurately reflect chlorine's role in pool chemistry. While chlorination contributes to overall water quality, it does not directly prime filters, stabilize pH, or lower water hardness. Each of these processes involves different chemicals and methods, highlighting chlorine's specific function in the oxidation of organic substances to maintain clean and safe swimming water.