The Kent Marine Nano Reef Part A-B is a combination calcium and alkalinity supplement formulated for nano reefs and smaller reef systems.Easy-to-use, 2-part liquid system simplifies reef supplementation vital for healthy coral and invertebrate growth Provides all important major, minor, and trace elements in proper ratios while increasing alkalinity and maintaining proper pHMinimizes overdose or adverse chemical reactions Each 16 oz bottle treats 946 gallons