The KH Guardian reagent is a special concentrated formulation to ensure the accuracy of the testing and safety of the reagent that goes back into your aquarium. Dr. Bridge carefully selected a pharmaceutical grade reagent for purity and stability. Each pack of concentrated KH reagent requires dilution with 1500 grams (+/- 1 gram) (please note that it is not ml) of pure water. The KHG reagent usage depends on testing frequency and the alkalinity of the water being tested. Typically, with an alkalinity of 7.5kH, the KHG will use approx. 2.2mls of reagent per measurement. With an alkalinity of 13kH, the KHG will use approx. 3.8mls of reagent per test. No preservatives are added to the concentrated KH reagent pack in order to protect the safety of living creatures in your reef aquarium.