Reef•Basis Iodide is a stabilized, safe iodide supplement, designed to nourish organisms that require iodine. It is particularly useful for soft corals of all kinds, particularly xenia, as well as gorgonians, hard corals, tunicates, marine worms such as feather dusters, sponges, macroalgae, and crustaceans, particularly shrimp. Growth rates in xenia and gorgonians will likely improve with it\'s use. It helps all corals and clams retain their coloration and shield against strong lighting. Reef Basis Iodide contains no gluconate or polygluconate. Iodine, while present in better salt mixes, is rapidly removed through ozone, skimming, carbon and other filtration and used up by inhabitants. It is necessary, therefore, to supplement it for maximum invertebrate and algae health, particularly if you have strong lighting. If you are propagating corals be sure to use along with Reef•Basis Calcium, Magnesium, and Strontium to provide proper minerals for aragonite growth. Continuum recommends that you maintain about .04 to .06 mg/l (ppm) iodide level in your aquarium, if measuring. Directions for use: -Shake well prior to use. -Add 1 capful (5 ml) per 50 US-gallons (200 L) of marine aquarium water 2 to 3 times per week. Do not overdose! This bottle will treat 19,000 Litres (5000 US Gallons)