Iodine And The Reef Tank

Adding Iodine to your reef tank can be accomplished in several ways. But before we discuss how o add it, it should be noted that there is no 100% agreement over whether or not Iodine should even be added. In the hobbyist sector of reef keeping, Iodine can also be used as a dip since it has antiseptic qualities as well. But this is anecdotal evidence, there have been no true scientific studies to verify the necessity or lack of necessity for adding Iodine. Unfortunately, reef keeping does not have a body of peer that reviewed the literature available, as much of our information comes from hobbyists and products manufacturers.

There are several ways to add Iodine :

A commercially prepared Iodine Supplement
Potassium solution
Sodium Iodide
Tincture of Iodine

Some facts about Iodine :

Iodine is a member of the halogen family of compounds, which also included Chlorine and Bromine.
Iodine is commonly found as I2. As a liquid it is a dull grey color, as a gas its a brown or purple.
Bioavailability Iodine ( the iodine that is considered useful to your reef critters ) is generally considered to be the iodine Ion I-.
Iodine is only slightly soluble in water, but dissolves well in solvent such as alcohol.
Iodine is considered to be reactive and thus should be dosed on a daily basis rather than weekly.
Due to its chemicals properties, iodine makes a good antiseptic and may also be used as a dip to cleansed wounds in coral tissues and eliminate certain disease.

How Much Iodine to Use :

Commercially available Iodine supplements generally use Potassium Iodide and several of them use a chelating compound such as EDTA. A buildup of EDTA may be harmful to your reef, the jury is still out this one, but many hobbyists try to stay away from chelated compounds.

Lugols solution is made up of 5% KI and 10% I2 by mass. Many people have switched from commercial iodine preparations to Lugols solution for economic reasons. A bottle of commercial preparation may last you six mths and cost $10. A pint bottle of Lugols cost approximately $15 and will supply you with iodine for the rest of your life. But Lugols solution too may contain a few problems, as discuses below.

Potassium Iodide ( KI ) and Sodium Iodide ( NaI ) can be considered together. Generally, a 5-10% solution of one of these is prepared and closed into the tank. These solutions will dissociate into positive ion K+ or Na + and the Iodide Ion I-.

Tincture of Iodine I2, alcohol and water. The alcohol is used to keep the iodine dissolved into solution. Tincture of iodine’s the least desirable method of adding iodine to your tank, it is acceptable for the use as an iodine dip.

How Much Iodine to Use :

You should look to have an Iodine concentration of 0..2 – 0.04 ppm of Iodine in your tank. Commercial test kits should be used to measure the present of the Iodine.

It is generally recommended that dilute solution of KI OR NaI be used 5-10% solutions are acceptable here. Commercial iodine preparations do not need to be diluted, they are very dilute anyways. Lugols solution can be diluted by simply using 1/4 Lugols and 3/4 of water ( by volume ). Dilution these solutions will prevent overdosing. Overdosing of Iodine can have very serious consequences on your tank, as it is both a strong oxidant as well as bactericidal. Too much Iodine can wipe out your whole tank.