Concentrated Strontium Supplement for All Marine Fish & Reef Aquaria Overview Highly-concentrated ionic strontium solution. Incorporated by corals, clams, and other reef-building invertebrates into aragonite, the mineral that is secreted as skeletal material. Stronger than most competing strontium solutions. Contains no unwanted organic material such as EDTA, gluconate, or polygluconate. Over 50% stronger than most competing products. Free of phosphate, silicate, and organic material. Formulated by a marine scientist.