+ is the essential element for plant and coral, also is the nutrient for marine fish and other aquarium life. When the Fe2+ is too low in aquarium, the coral and other aquarium life will be color fading. CORAL REEF Fe2+ Support contains lots of Fe2+ and other nutrient element and could supply for the growth of coral and plant. Easy absorb by coral and plant by ion. Remark: Please use as soon as possible after you open the vacuum package, because Fe2+ will easily change into Fe3+ when meet the air.