Bulk Reef Supply carries three Hanna Checker Colorimeters –Alkalinity, Calcium and Phosphate as well as all the reagents for all these tests. These small, innovatively designed instruments are easy to use, accurate and very affordable. Test results in four simple steps: zero the instrument with water sample, add the reagent to the sample, place vial in the Hanna Checker, press the button and read the results on the large, digital screen.