Calcium and magnesium salts dissolved in water cause hardness which can lead to scale. A standard solution of chelant is used to titrate the hardness in the sample. The indicator changes from red to blue at the titration end point. We offer a variety of hardness test kits including total, calcium, and trace with powder and liquid indicators. Our hardness test kits have a low end sensitivity of less than 0.5 ppm to better detect trace hardness levels. Each kit is packaged in a durable plastic case and includes all items to complete approximately 60-75 tests.