Economize by Creating Your Own Accurate KH Test Fluid with Highly Concentrated KH Keeper Reagent – up to +/- 0.01 dKH! This concentrated reagent is compatible with the Reef Factory KH Keeper Plus and can be mixed with 9 L of RO/DI water to yield 10 L of test fluid, equivalent to approximately 1,429 tests. The number of tests may vary depending on the alkalinity of your aquarium water, with higher levels requiring more reagent and lower levels requiring less. Access your test results and measurement history easily through the app.