pH refers to the measurement ...

pH refers to the measurement of the hydrogen ion concentration in a water. The saturated pH is a calculated value at which a dissolved salt could begin to precipitate from solution. For calcium carbonate scale, for example, the pH of saturation is calculated from the measured alkalinity and calcium concentrations, and is usually done at the highest temperature expected in a heat exchanger (for example, a power plant condenser). The pH of saturation is used to calculate scaling indices, such as the Langelier or the Ryznar saturation indices.