which kind of iodine is it? there are several different "variations" of what we call iodine. the most common are sodium iodide, Potassium iodide and tincture iodide. tincture iodide is not the best way to add iodine to your tank water, since iodine is not very water soluble tincture uses alcohol to help with solubility. Potassium iodide is KI and Sodium iodide is NaI. In order to have the antiseptic effect from iodine you need to create an iodide ion. So when you add NaI to your tank water at a .5-1/10 solution then you get potassium chloride and I- or Sodium Chloride and I-. The most cost efficient way (if you can) is to purchase Lugols Iodide which is a solution of potassium iodide and Tincture iodide and water. But again lugols contains tincture iodide and alcohol or iodate IO3. As long as you have low nitrate readings your tank and coral should be able to convert that iodate to I- with natural enzymes with no problem. or you may want to try and use and enzyme solution called nitrate reductase to aid