Seachem's Reef Salt" is a chemically sound blend of salts designed to replicate natural reef waters. It is specifically formulated for the reef environment and will provide ideal seawater concentrations of magnesium, calcium, and strontium with proper alkalinity and pH for closed reef aquarium systems. It contains all essential major, minor, and trace components found in natural reef waters, but contains no toxic or non-essential components such as nitrate, phosphate, silicate, arsenic, cadmium, or beryllium. Reef Salt" dissolves quickly and completely and is ready to use in only a few minutes. Reef Salt" will support and promote enhanced calcium and alkalinity stability for those wishing to maintain calcium above Natural Sea Water (NSW) levels (400 mg/L) as well as providing NSW levels of bromide (65 mg/L). Aquarium Use Only! Keep Away from Children!