The E.S.V. Potassium Iodide Solution is a very pure form of iodide. Iodide is an important micro-nutrient for many marine plants. It has also been suggested that iodide may play an important role in enhancing a coral's ability to adapt to rapid changes in light intensity and spectrum. The recommended dosage is 1 drop per gallon per week (1 ml per 20 gallons per week).