HI772-26 are the replacement reagents Marine Alkalinity (dKH) Checker® HC - HI772. Achieve fast and precise measurements with Hanna Instruments Marine Alkalinity Reagent. These high quality reagents are pre-measured and follow the colorimetric method. Add solution to the sample, he reaction will take place and the Marine Alkalinity Checkers will determine the concentration from the color that is produced. Results will be displayed in dKH for the HI772 Checker. 25 tests.