The HI93720-01 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents follow an adaptation of the calmagite method. The reaction between calcium and the reagents causes a red tint in the sample. By simply adding the reagents to the sample, a reaction will take place and a compatible benchtop or portable meter can be used to determine the concentration from the color that is produced. The results will be displayed in mg/L (ppm) as calcium carbonate (CaCO3). These reagents are designed to be used with samples that have an expected range of 0.00 to 2.70 mg/L calcium hardness.