Adding Iodine to a Reef Tank

Mekaeel

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Hey crew,thought this article will help us all in regards to addition and benefits of iodine.

Adding Iodine To the Reef Tank

By Eric Edelman
Adding Iodine to your reef tank can be accomplished in several ways. But before we discuss how to add it, it should be noted that there is no 100% agreement over whether or not Iodine should even be added. In the "hobbiest" sector of reefkeeping, Iodine has been found to benefit soft corals, assist in calcification in stony corals, and enable crustaceans to molt properly. 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, reefkeeping does not have a body of peer reviewed literature available, much of our information comes from hobbiests and product manufacturers.
There are several ways to add Iodine:
  • A commercially prepared Iodine Supplement (Coralife, Kent, Thiel, Wilkens, etc....)
  • Lugol's solution
  • Potassium Iodide
  • Sodium Iodide
  • Tincture of Iodine
Some facts about Iodine:
  • Iodine is a member of the halogen family of compounds, which also include Chlorine and Bromine.
  • Iodine is commonly found as I2. As a liquid it is a dull grey color, as a gas it's a brown/purple.
  • Bioavailable Iodine (the iodine that is considered useful to your reef critters) is generally considered to be the Iodide Ion I-.
  • Iodine is only slightly soluble in water, but dissolves well in solvents such as alcohol.
  • Iodine is considered to be reactive and thus should be dosed on a daily basis rather than weekly.
  • Due to it's chemical properties, iodine makes a good antiseptic and may also be used as a "dip" to cleanse wounds in coral tissues and eliminate certain disease.
Types of Iodine you can 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 on this one, but many hobbyiests try and stay away from chelated compounds.
Lugol's solution is made up of 5% KI and 10% I2 by mass, in water. Many people have switched from commercial iodine preparations to Lugol's solution for economic reasons. A bottle of a commercial preparation may last you six months and cost $10. A pint bottle of Lugol's costs approximately $15 and will supply you with iodine for the rest of your life. Lugol's solution may contain a few problems, as I will discuss below.
Potassium Iodide (KI) and Sodium Iodide (NaI) can be considered together. Generally, a 5-10% solution of one of these is prepared and dosed into the tank. These solutions will dissociate into the positive ion K+ or Na+ and the Iodide Ion I-.
Tincture of Iodine is I2, alcohol, and water. The alcohol is used to keep the iodine dissolved into solution. Tincture of iodine is the least desirable method of adding iodine to your tank, it is acceptable for use as an iodine "dip".
What Happens to Iodine In The Reef Tank

Again, I'd like to mention that the Iodide Ion (I-) is considered to be the most bioavailable of the forms of iodine. Dr. Marlin Atkinson presented his findings at WMC and indicated that KI was a more beneficial method of iodine addition compared to the Lugol's solution due to the I2 concentration in the Lugol's.
In regards to the I2 issue, I2 will break down into I- and IO3- with several intermediates that aren't important since they're short lived. The iodate ion (IO3-) is of concern. This is the little guy that can accumulate in your system, not the I2. There is an enzyme that can convert the IO3- into I- which cures the problem. HOWEVER, the enzyme is called nitrate reductase and in many hobbyists tanks is overburdened with nitrates, and thus cannot accoplish the IO3- ===>> I- conversion. This enzyme is found in photosynthetic organisms. The Iodide ion (I-) is considered to be bioavailable where the Iodate ion (IO3-) is not.
Anoxic areas within your tank (inside rock, under the sand bed, under a plenum) can provide a mechanism to convert the Iodate to the Iodide ion in theory, but whether this actually happens is anyone's guess at this point. So it is entirely possible that some hobbyists who are using Lugol's with good results may have the facility in place to accomplish this conversion. Others may not, which leads to an Iodate buildup in the system.
The iodide ion then is the desirable form of iodine, and it's what we want to put into our tanks. Iodide ions are considered to be necessary for calcification in stony corals, general health of soft corals, and molting in crustaceans.
How Much Iodine to Use

You should look to have an Iodine concentration of 0.02 - 0.04 ppm of Iodine in your tank. Commercial test kits as of this writing are available from Salifert and Seachem.
It is generally recommended that dilute solutions 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. Lugol's solution can be diluted by simply using 1/4 Lugol's and 3/4 water (by volume). Diluting these solutions will prevent overdosing. Overdosing Iodine can have serious consequences on your tank, as it is both a strong oxidant as well as bacteriocidal. In other words, if you add too much iodine, you can wipe out your tank.
Conclusions

If you believe that iodine is necessary to the health of your corals and crustaceans, then you should be adding it to your reef tank.
That being said, if you're comfortable using chemicals that aren't labelled for "Aquarium Use", Lugol's is available at a pharmacy store (you may need a prescription in some states). Sodium Iodide and Potassium Iodide can be obtained at chemical supply houses. And pet shops and mail order houses will carry the commercially available preparations along with the test kits. The Iodine test kit is pretty much essential if you're going to be adding Iodine to your tank. My recommendation is to stay away from the Tincture of Iodine, it contains alcohol as well as the least amount of bioavailable iodide ions.
Happy ReefKeeping!

http://www.reefs.org/library/article/e_edelman2.html
 
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thanks alot mek

I BELIEVE IN IODINE:thumbup:
i use alpha chem(50ml) for R8 a bottle,dilute it in 200ml of ro water.(thanks jacquesB)
 
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yip, and lappiesreef did some test and saw that some of the product on the shelfs doesn't even contain allot of iodine
 
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I have been testing for Iodine for the last 6 months and I have never had to dose. WC's must be dosing the system sufficiently ??
 

jacquesb

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Warr - it seems quite viable that the salt you use in your water changes contains enough iodine to keep your fish happy....

I started dosing iodine because of my nemmies..... A LOT of international sites suggest that iodine should be dosed for the nemmies.... So, therefor I dose it. BUT, I dose VERY little compared to the amount of water I have...
 

jacquesb

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BTW: Many thanks for this interesting article Mekaeel.... I dunno - even though this guys talks of the tincture of iodine that's not good.... I have never really seen any negative effects because of me dosing it.... So, I will most likely continue...
I don't have major nuisance algae problems anymore.... neither cyano outbreaks....
 
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Jac I get the feeling the iodine tinctures we get here is actually just potassium iodide...
Maybe thats why there is no negative effects...
I strated dosing the iodine since last week. Made a huge difference in my cyano. They actaully went brown and dissappeared...replaced by diatoms though :( but all part of the process ;)
 

jacquesb

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LappiesReef - I think that you are QUITE correct. I think that I actually read that on one of the bottels..... BUT diatoms are not so bad as cyano Lappies - MUCH rather diatoms than cyano...
 
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True enough Jac :) It's probably food for lots of stuff any way...I try and blow it around everyday and rake the gravel to make a nice storm of ditritus and diatoms...
 
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Dr Ron Shimek did a study of @ 20 different reef tanks where people were NOT DOSING and found that every single one of the tanks had Iodine levels in excess of NSW (Natural Sea Water).

The 1.0 on the scale represents NSW and the Iodine is the I on the far right. It's in our salt mixes and it is also in a lot of the foods we feed our fish. (primarily from the algae portion of these foods).

Figure8sm.jpg


I don't recommend dosing Iodine unless you keep gorgonians, tunicates (sea squirts), sponges, or a lot of macroalgaes.

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Mek if you look at the graph there are tanks that are insanely over the norm. The one tank is bordering on 50000x more iodine than NSW. I always thought it weird that my tank didn't need Iodine, this confirms it :thumbup:
 
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Hi mantisfreak.what about tanks where the fishload is low or there is very little feeding eg once in 2 days and water changes arent done regularly,surely iodine should be dosed?
I think we should simply use common sense and think things through just like you did above. You could easily end up in a situation where you had low Iodine....especially if you're keeping sponges or macroalgaes (or even algae in a refugium).

Let me give you another scenario. You have a high fishload that includes a lot of tangs. As a result, you are constantly feeding algaes and foods containing algae to the tank. In that situation, a water change likely lowers the Iodine levels as opposed to raising them.
 

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