Neptune Reagent for Neptune Trident 2-Month Reagent Kit (based on the standard testing schedule of 4x Alk / 2x Ca / 2x Mg per day). The reagent kit contains at least 240 alkalinity tests and 120 tests each for calcium and magnesium. Neptune advises not to stock more reagent than needed for one year. The Trident Reagent Kit includes: Two bottles of Reagent A (to be replaced monthly), one bottle of Reagent B (to be replaced every two months), one bottle of Reagent C (to be replaced every two months), and one calibration seawater sample bottle