Reef Basis Sustain Iodine is a unique, multicomponent iodine release system, 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 use. It helps all corals and clams retain their coloration and shield against strong lighting. Reef Basis Sustian 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 Coral Exponential TM to provide naturally ratioed amino acids for accelerated tissue growth along with Reef Basis Calcium, Magnesium, and Strontium to provide proper minerals for aragonite growth. Also, use Coral Elements N to add vitamins and trace minerals specifically designed for corals. Continuum recommends that you maintain about .04 to .06 mg/l (ppm) iodide level in your aquarium, if measuring.