Iodine and Protein Skimmers...

[Crustaceo Mutoid]

Anyone know how much Iodine/Iodide is removed by a skimmer on the first pass? And if it's a considerable amount, how do you maintain a consistent level if you use a skimmer?

[3_high_low]

precisely 0.3452 mmols/min

Just kidding. I seriously doubt anyone on the planet can tell you. I hear Salifert makes a good test kit though.

I just blindly add 6 drops daily in my 55gal. It seems to keep the softies happy. I also add 4ml Strontium/moly every 4 days. Both are Kent products. I skim w/ a Remora Pro 24/7.

Good luck

[Randy Holmes-Farley]

I don't believe that skimmers remove iodine. There are no forms of inorganic iodine that absorb at air/water interfaces.

IMO, this is a myth that has long been around without any scientific basis of which I'm aware.

FWIW, iodine depletion has been noted to be just as fast in tanks with no skimming as in those with skimming.

What can take place is that skimmers may remove organisms that themselves contain, and perhaps have selectively sequestered, iodine.

Skimmers may also remove organic iodine compounds, if any substantial amounts are present (which is, as far as I know is uncertain).

[FishHead]

If your changing 20% of your water monthly - I don't think adding anything is necessary.
I know some will disagree, but that works for me.
I have a bottle of Kent iodine and a bottle of Kent Lugol's if you'd like them.

[Crustaceo Mutoid]

Thanks for the quick replies everyone! The only reason I asked this question was on Sunday I dosed one drop of Kent's Lugol's Solution to my 13 gallon nano. Last night I tested for Iodide/Iodine using the SeaChem test kit. The result was practically nil, so I re-tested and came up almost zero again. That Lugol's stuff claims on it's labeling that it is "super-concentrated" and one drop will treat 20-25 gallons for a week! I was stumped as to why one day later there was none to be found in my tank? Thus it led me to post this skimmer question. Any idea's here anyone? (please assume that I am testing correctly )

[Randy Holmes-Farley]

IME, iodide depletes from NSW levels to much lower levels in 1-2 days. You should test 15 minutes after addition if you want to be sure to see it.

[Crustaceo Mutoid]

Randy,

Your right, iodine depletes at a astonishing rate. I found this article using the RC search engine on Iodine and highlighted the reduction rate in blue. The following is taken from it;

"Elemental iodine is unstable in seawater and is found in the elemental form in vanishingly low concentrations. It initially seems to undergo this reaction: I2 --> I- + I+. The I+ then undergoes a complex series of reactions.
One of the iodine additives promoted for reef aquarium use is Lugol’s solution, which in veterinary practice is sometimes used as a topical disinfectant. Iodine is quite insoluble in water, but in the presence of excess I-, the I2 is converted to I3-. This trick allows one to get a substantial amount of what is essentially elemental iodine into a purely aqueous solution. Lugol’s solution consists of 10 grams of KI and 5 grams of I2 per 100 milliliters final volume. This makes the solution almost exactly 1 molar total iodine, with 0.602 molar I- and 0.394 molar I atom equivalent. It has been shown that when elemental iodine is added to actual seawater samples containing naturally occurring dissolved organic substances, the minority of elemental iodine (17 percent) was oxidized to iodate, the remainder being reduced with the involvement of organic substances dissolved in the water (Truesdale et al. 1995). It is also interesting to note that inorganic iodine was not conserved in these experiments, so presumably some iodinated organic compounds were formed directly in the water. So, the expectation is that with the conversion of the elemental iodine in Lugol’s solution mainly to iodide through the series of intermediates that formed, over 90 percent of the total iodine in Lugol’s should ultimately become iodide.

The disappearance of molecular iodine is rapid. It has been observed that the apparent rate constant for reduction of I2 added to seawater varies from 0.030 and 2.31 per minute. The ephemeral existence of the yellow-colored molecular iodine casts some doubt on its ability to provide any significant or meaningful photoprotection for light-shocked animals. The anecdotal evidence suggesting that addition of Lugol’s solution to aquaria aids in photoadaptation (Delbeek and Sprung 1994) must find another mechanism other than simple light absorption by molecular iodine or triiodide ions. For example, iodide is known to react efficiently with some toxic byproducts of photosynthesis. This might acount for the anecdotal evidence mentioned by Delbeek and Sprung (1994).

Although the elemental iodine should rapidly become iodide and intermediates, it may take some time for these intermediates to clear from the water. Some of those intermediates are toxic. Based on Marlin Atkinson’s presentation at the 1997 Western Conference, and his suggestion that it may be prudent to add only iodide salts to reef aquaria, a few aquarists have offered observations leading them to believe that Lugol’s solution may be quite detrimental to some organisms, Xenia being the most often cited example. None of these observations have been controlled experiments, nor were they conducted in replicate"

After reading this article it makes me wonder what chemical bi-products have been produced in my tank from the use of Iodine, specifically Lugol's Solution?

You can read the full article here:
http://www.animalnetwork.com/fish2/a...io/default.asp

[Randy Holmes-Farley]

Yes, Craig's article is a nice summary of some iodine chemistry.

[Crustaceo Mutoid]

So Randy... what are you currently doing/not doing as far as Iodine supplementation goes?

[Randy Holmes-Farley]

Once or twice a week I dose the NSW equivalent level of iodide to my tank. That is, I dose to about 0.02 ppm I- once or twice a week. I use sodium iodide.

Despite the reasonable concerns that many have suggested of not dosing something that you do not routinely test for, I'm not worried about that in this case.

Iodide is so rapidly depleted in all tanks that I've seen tested, that I think it very unlikely that anyone could overdose on I- by dosing the NSW equivalent amount once per week or less.

One caveat is that I'm not sure any fully closed system tanks (i.e., no nutrient export of any type, such as skimming, algal scrubbing, organism removal for trading or sale, very small water changes) have been tested in this fashion. In that case, I'd be more careful about iodide.

[saltshop]

Randy,

I have always been unsure of what exactly this statement from Dr. Bingman's article is trying to say....so since you are around today I figured I would ask you.

"It has been shown that when elemental iodine is added to actual seawater samples containing naturally occurring dissolved organic substances, the minority of elemental iodine (17 percent) was oxidized to iodate, the remainder being reduced with the involvement of organic substances dissolved in the water (Truesdale et al. 1995). It is also interesting to note that inorganic iodine was not conserved in these experiments, so presumably some iodinated organic compounds were formed directly in the water."

Is he saying that 83% of the iodine is more or less becoming part of larger organic molecules or that it is simply being reduced from I2 to another form of Iodine through the interactions with organics? I was just curious if it is the former and it becomes part of organic molecules then are hobbyist test kits still able to detect it? I would think if that were true it would help to explain the rapid depletion as far as trying to test for it goes. I would also assume that the iodine would still make its way into the food chain through the organic molecules or be skimmed out of the water...maybe, maybe not.

[Randy Holmes-Farley]

It isn't especially clear, but here's my paraphrase:

When iodine is added to organic-containing seawater as I2, 17% ends up as iodate (IO3-), with most of the remainder becoming I-. However, if you add up the I- and IO3- concentration, you cannot account for all of the I2 used, so some of it must have become incorporated directly into organic compounds as iodo-organics.

As to the depletion, IME, I- is depleted rapidly and IO3- only very slowly. The interchange between the two species seems rather slow in reef tanks. I've tried to find out more about natural iodo-organics in seawater, but there are not many people studying them, and the few that are seem mostly interested in organics that are released from the ocean to the atmosphere.

[SciGuy2]

Randy,

I've been wondering what your thoughts would be on iodine. In light of what Dr. Ron has been saying, that is. Here's a thread that I'm certain you've heard about.

http://archive.reefcentral.com/vbull...dine+and+toxic

Not provoking an arguement, just fostering scholarly discussion.

Thanks,
-Sci

[Randy Holmes-Farley]

Well, I have no idea what the basis of Ron's assertion that iodide is toxic to xenia at higher temperature is. Since he says "I suspect", I suspect that all it is is a suspicion.

FWIW, xenia grew fine in my tank for years at 81 deg F and frequent additions of iodide, but not substantially over NSW levels. Perhaps he means overdosing with iodide, a practice which I, of course, discourage.

Ron?

[Crustaceo Mutoid]

He also mentions that at lower temps Iodine is not much of a factor in harming Xenia.

[SciGuy2]

Randy,

Thanks for posting over at Dr. Ron's forum. I'll follow the discussion over there.


Crust,
I think Dr. Ron means lower than 80 degree F as being low temperature. I'll let Dr. Ron speak for himself over at the other forum.

Thanks,
-Sci

[Randy Holmes-Farley]

crust: I corrected my typo to read higher, not lower. Thanks for catching that.

[Crustaceo Mutoid]

np Randy

[saltshop]

BTW- Thanks Randy for the earlier explanation of what was being said in the article, it helped to clear things up quite a bit. One more quick question, does Iodate then build up in the tank as its depletion is "slower" or is it depleted before being built up? Just curious. Thanks again.

[Randy Holmes-Farley]

When I dosed iodate to my tank at a rate comparable to my standard iodide dosing, iodate built up to substantial, coral-impacting levels, while iodide did not.

Consequently, I would not recommend that people dose iodate.

Since dosing substantial amounts of Lugol's apparently has a similar effect as iodate dosing (at least as reported in that article), I'd avoid that as well. I don't, however, have any information on whether it builds up in normal Lugols dosing schemes.

Since iodide is inexpensive and readily available from ESV and eslewhere, I can't see any reeason to dose Lugols.

[tatuvaaj]

Randy,

I remember reading somewhere that potassium iodide is "unstable" chemical and it should be stored in cold and dark place.

Any truth in that statement ?

TIA

[Randy Holmes-Farley]

Iodide can slowly oxidize to iodate and I2. Kent's product says it has stabilizers, which presumably prevent this reaction. I keep mine in my basement, where my refugia are. It's fairly cool, and not brightly lit.

[WaterKeeper]

Saw this tread a few days ago but didn't have time to read it all until tonight. Very interesting.

One point, which supports comments earlier in the tread, is that Lugol's contains free iodine. I would think this reactive, free iodine would easily oxidize DOC in the tank and form halo-organic compounds of iodine. These would not show up in common test kits. I am not sure but these could accumulate and reach toxic levels in the tank.

Would be interesting to see some gas chromatograph/mass spectrograph data on a tank regularly dosing Lugol's solution.