Strontium & Molybdenum Supplement provides bio-available strontium for lush growth of purple, pink and green calcareous algaes, snails, hard tube worms and clams, Magnesium is added to make up for deficiencies in some of the newer brands of sea salt mixes, Potassium & molybdenum are added to assist the symbiotic algae growing in coral and other invertebrates tissues, Corals will open more and stay attached to their skeletons better, with regular use, Phosphate & nitrate free! Contains no gluconates, EDTA, or other organics to raise DOC levels, as many competing products do, For best results, Use Kent Kalkwasser Mix, or Concentrated Liquid Calcium first, SKU: RPS13527