Precision Iodine is a highly concentrated, bio-available Iodine supplement that is ideal for Marine Fish and Reef aquariums. Proper Iodine levels will help corals maintain their natural color, protect them against bleaching and help them open more fully. Iodine also assists crustaceans in performing the important process of molting. In addition, Iodine has important properties for fish. It will aid the metabolism of fish by providing Iodine for the thyroid gland, which helps maintain strong coloration and a vigorous appetite. Precision Iodine is made with high quality (USP Grade) chemicals, which ensures you will not be adding unwanted amounts of metals or organics to your aquarium. 1 capful (.17oz or 5mL) of Precision will increase iodine levels by approximately 0.05 ppm (mg/L) per 25 gallons (94.5 liters).