Alkalinity Reagent - 25 Tests - Hanna Instruments

The HI772-26 reagent set keeps your Hanna Marine Alkalinity Checker HC running without interruption. Designed exclusively for use with the HI772 Checker, these replacement reagents deliver the same pre-measured, ready-to-use convenience as the original kit — no pipetting, no preparation, and no risk of user error from measuring out chemicals. Results are displayed directly in dKH, the unit most reef aquarists work with daily.

The chemistry behind the HI772-26 follows a colorimetric method: when added to a seawater sample, the reagent triggers a color progression ranging from yellow to green to blue. The Checker reads the resulting color and calculates the alkalinity concentration within a range of 0.0 to 20.0 dKH — broad enough to capture both low and elevated alkalinity levels in a reef system.

Reagent quality is consistent across batches because they are manufactured in a controlled facility using high-purity chemicals. Every packet is labeled with a lot number and expiration date, so you can verify freshness before use and maintain records for tank management purposes. This traceability is particularly useful for hobbyists who track alkalinity trends over time and need confidence that reagent variability is not skewing their data.

Each box contains enough reagent for 25 tests. For reef tanks where alkalinity is tested multiple times per week, a single box may last only a few weeks, so keeping a spare set on hand is advisable. These reagents are not compatible with other Hanna Checkers — confirm you are using the HI772 before ordering.