Elos Aqua Test Kit - Carbonate Hardness High precision: thanks to the use of calibrated droppers L NIST validation: each batch is validated using NIST (National Institute of Standard and Technology) High number of test per kit: up to 60 test (with a standard level of 10 dKH) L "Safe reagents": reagents and testing procedures are based on Low Risk Reagents. None of our test ki