Neptune Systems recommends keeping on hand no more Trident reagent than you might expect to consume within the next 12 months.
2-month reagent kit (based on the default testing schedule of 4-Alk/2-Ca/2-Mg per day). The reagent kit has at least 240 alkalinity tests and 120 tests each of Calcium and Magnesium.
Kits include:
Two bottles of Reagent A (changed every month),
One bottle of Reagent B (changed every two months)
One bottle of Reagent C (changed every two months),