The HI755-26 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Marine Alkalinity Checker® HC. These reagents follow the Colorimetric Method in which the reaction causes a distinctive range of colors from yellow to green to blue to develop. By simply adding the solution of HI755-26 to the sample, the reaction will take place and the Marine Alkalinity Checkers will determine the concentration from the color that is produced. The results will be displayed in ppm of CaCO3 . These reagents are designed to be used with samples that have an expected range of 0 to 300 ppm CaCO3 .