HI779-25 are high-quality reagents, ensuring users obtain fast and accurate measurements with the Checker® HC HI779. These reagents follow the Phenol Red method in which the reagent produces a color change in the sample, linked to the pH value. By simply adding 5 drops of HI779-25 reagent to the sample, the reaction will occur and HI779 will determine the concentration based on the color produced, which can vary between shades of yellow or red. Results will be displayed in pH with 0.1 pH resolution. The HI779-25 reagent pack allows for 100 tests.