NanoReef Part A contains calcium, magnesium, strontium, iron, and many other important elements. When used with NanoReef Part B, it provides all necessary major, minor, and trace ions in proper ratios to maintain proper water parameters in nano reefs and other small reef systems. Free of phosphate and other undesirable substances. Calcium and alkalinity supplements 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 pH. Minimizes overdose or adverse chemical reactions. Each 8-ounce bottle treats 475-gallon.