Which factor affects the chlorine demand in pool water?

Chlorine demand in pool water is influenced by multiple factors, and among these, water temperature, pool size, and the number of swimmers all play significant roles.

Water temperature impacts chlorine's effectiveness because warmer water tends to increase the rate of chemical reactions, including those that use up free chlorine. As the temperature rises, chlorine can be consumed more quickly, necessitating a higher dose to maintain effective sanitation levels.

The size of the pool also affects chlorine demand, as a larger body of water requires more chlorine to achieve and maintain desired levels of sanitation. If there are more gallons of water, it takes more chlorine to disinfect the entire volume compared to a smaller pool.

The number of swimmers contributes to chlorine demand as well, since each individual introduces organic matter, such as sweat, oils, and other contaminants, which chlorine must work to sanitize. More swimmers generally result in higher chlorine consumption to keep the water clear and safe.

By acknowledging that all these factors cumulatively affect chlorine demand, it becomes evident that the correct answer reflects the complexity of maintaining water chemistry in a swimming pool environment.