The HI731335's locking index tab ensures the cuvette is inserted in the same orientation for both blank measurements (zero) and sample readings

Formula: FDA-approved citric acid (food-safe)

featuring automatic temperature compensation

Swimming pool and spa water chemistry monitoring

for increased accuracy with manual trimmers for easy adjustment

Hanna Marine Calcium Checker HC Calibration Check Set - HI758-11 PFAS filtration The HI731335's locking index tabThe Marine Calcium Checker HC Calibration Check Set HI758 11 provides a simple solution to validating the Marine Calcium Checker HC HI758 that has a range of 200 to 600 ppm calcium. This high quality set of standards is manufactured in our state of the art facility and comes supplied with a Certificate of Analysis. The Certificate of Analysis provides the lot number, reference values and expiration date for traceability when certifying the CheckerHC.