What does alkalinity measure in pool water?

Alkalinity measures the ability of pool water to resist changes in pH, which is crucial for maintaining water balance. Specifically, it indicates the concentration of bicarbonates, carbonates, and hydroxides in the water, acting as a buffer system. A higher alkalinity means the water can better withstand fluctuations in acidity or basicity, which helps to stabilize pH levels. This stability is vital for ensuring that the chlorine and other sanitizers in the water remain effective in keeping the pool clean and safe for swimmers.

The other answers do not pertain to alkalinity: chlorine levels indicate the pool's sanitization capacity, dissolved solids reflect overall water quality including impurities, and temperature pertains to comfort and chemical reactions but not to alkalinity.