Water, with exception to distilled water, contains dissolved salts (magnesium and calcium carbonates). The concentration of these salts determines the water hardness, which can be expressed in calcium carbonate or magnesium carbonate. The sum of these two represents the total hardness level. In addition, this parameter is also related to teh phenomenon of pipe rusting in water heating and cooling systems, reverse osmosis and demineralization plants.

Supplied with 2 sample cuvettes with caps, 9v battery and instructins.