Vibrant Sea Salt by Seachem offers an ideal blend of highly concentrated, fast dissolving salts to benefit all marine, reef and closed reef aquarium systems. This blend is nitrate and phosphate free, safe for all saltwater fish and plants. All essential major, minor, and trace components found in natural seawaters, including enhanced potassium levels are combined, along with accurate seawater concentrations of magnesium, calcium, and strontium with proper alkalinity and pH; truly replicating marine and reef waters. Vibrant Sea produces more saltwater from using less salt. This is possible because this blend is a crystalline compound, containing no water which also creates an exceptional consistency from batch to batch. For your convenience, Vibrant Sea makes maintenance simple with the included zip tie inside to easily reseal your bag.