Red Sea salt is a premium sea salt formula, based on the natural salt harvested by solar evaporation of the waters of the exotic. It is enriched with other fine minerals to faithfully replicate natural seawater for your aquarium. Salt has become famous for its favorable effects on invertebrates. A small batch process to ensure homogeneity of salt mixture. Every batch is biologically and chemically tested for quality control. Can be mixed to any salinity. Available in 50-gallon. Includes 3 pieces per pack.