Parts Per Million
Parts per million (ppm) is the unit used to express the concentration of dissolved substances in pool water, equivalent to milligrams per liter (mg/L).
Definition
Parts per million (ppm) is the unit used to express the concentration of dissolved substances in pool water, equivalent to milligrams per liter (mg/L).
Typical Values: FC: 1–3 ppm; TA: 80–120 ppm; CH: 200–400 ppm; Salt: 2,700–3,400 ppm
In Plain Language
One ppm equals one milligram of substance per liter of water, or one part substance per one million parts of water by weight. For pool management, ppm is used to express chlorine, pH adjustment chemical effects, calcium hardness, alkalinity, CYA, and salt concentrations. All pool test kit readings and target ranges are expressed in ppm.
Why It Matters
Understanding ppm as a measurement unit is prerequisite for interpreting all pool chemistry test results and chemical dose calculations.
Typical Values
FC: 1–3 ppm; TA: 80–120 ppm; CH: 200–400 ppm; Salt: 2,700–3,400 ppm
Last reviewed: 2026-06-01