Inland Seas Marine and Reef Buffer replenishes the carbonate and bicarbonate required to maintain or increase the alkalinity of captive marine systems. Alkalinity (carbonate hardness) in captive marine systems constantly decreases as biological processes remove carbonate, and produce acids that neutralize carbonate. Proper alkalinity should be maintained around 2.5-2.9 me (7-8 dKH) for marine fish tanks and 3.2-3.6 me (9-10 dKH) for reefs.