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FAQs on Iodine Use, Supplements,  Troubleshooting/Fixing

Related Articles: Iodine in Marine Aquarium Systems by Marco Lichtenberger, Marine System Additives

Related FAQs: Iodine 1, Iodine 2, & FAQs on Iodine: Rationale/Use, Iodine Testing/Test Kits, Sources of Iodine/Supplements, Dosing, Interactions, & General Supplements, Calcium

Too little (for too long) or too much I2 can be trouble.

Iodate 1/14/10
Hello crew,
<Hi Laurie>
I've referred to your site many many times over the past years and thank you for the valuable information.
I have a mature, five-year old saltwater tank. I've just recently upgraded my lighting, enabling me to now support corals.
Since I have added the corals, I thought it would be wise to check on the iodide level, wondering if I'd need to increase iodide supplementation. (I was adding 5 ml Seachem Iodide on even days to my 110 gallon tank, which
resulted in .06 ppm iodide - perfect, right?)
<Yes... but I would add on a punctuated basis... perhaps once a week after your water change regimen>
I couldn't get a valid reading from my Seachem test kit, so I supposed that it had probably expired.
While shopping for a new kit, I ran across Salifert's version which tests for iodide, iodine, and iodate. I ordered this one, and ran my first test.
The good news is that I got the same .06 iodide reading, but the bad news (I think) is that I got an off-the-charts iodate reading (>.2 ppm).
<Happens... and one reason I encourage only periodic dosing of I2>
I've read and re-read the information provided with the test kit regarding iodide and iodate levels, but I can't seem to find a definitive answer on what a high iodate reading really means, and which of these elements (iodide, iodine, and iodate) our marine specimens actually use. Salifert's web site does not have any additional information.
<Mmm, the valence state of Iodine changes to extents with local chemistry, physical properties of the water; but often it is the initial preponderance of one or t'other that results in such tests>
There is one piece of interesting information in the test kit instructions, under Interferences:
"The presence of strong reducing substances
<Mmm, yes... ORP, RedOx Potential... alters the valence state...>
such as ascorbic acid will also give a false value. Some supplements contain ascorbic acid."
<Mmm... I would not have put this statement in a circular... No supplement has this much Vitamin C... This information is spurious, unnecessary>
More on this in a moment...
So, my question is, what do I really need to be testing (iodide or iodate) and is this high level of iodate toxic?
<Really not generally an issue... Unless one is "really pouring it in" in concentrated doses... Again, I would just do your "normal dosing" once a week. Am sorry to state that I/we/WWM has not produced a comprehensive set
of declarative statements (an article) re Iodine/ide/ate and its practical use. The collection of FAQs re can be accessed here:
and the linked files above.>
I perform 10% water changes biweekly (sometimes 5% weekly) along with cleaning or changing the filter media (paper and carbon).
<The carbon will remove...>
I recently switched to Red Sea Pro salt, which greatly increased the magnesium level (~1200 ppm now; was ~900 before), but do add a small amount of mg and sr twice a week (Seachem Reef Advantage). I supplement with
Seachem Reef Plus (Amino Acids and Vitamins) twice a week.
<Good products and good to stay with one manufacturer's line>
BTW - the first ingredient listed is ascorbic acid. And, as mentioned, add 5 ml of Seachem Iodide every other day. I do not need to add calcium - that usually tests between 450 - 500 ppm.
<I'd let slip into the 300's ppm range>
pH is 8.4; carbonate hardness is 10 dKH.
All of the coral look really healthy. For example, Zoanthid polyps are all fully opened; xenia is growing very quickly and spreading up the live rock.
<Good. A much better guide/test than any colorimetric assay>
Thanks for your help. I'll be very interested in your thoughts about this.
Best regards,
Laurie O.
<Sorry to be so scant here. I am not trying to be disingenuous, but I want to post "something" to the general public that is simple, straight-forward, applicable... and w/o potential dire consequence. Bob Fenner>

Iodine level question Bob, I have a 58 gal tank with about 120 lbs of live rock, several colonies of mushrooms, and I have just added a green button polyp rock and a leather coral. The setup is about 9 months old. Fluorescent lights (2 actinic/2 trichromatic) for 8 hours/5 hours per day. Last test readings were PH 8.2, Alkalinity 4.3  <assume meq/l> , Nitrite 0, Nitrate 9, Calcium 430, Iodine/Iodide 0. About a month ago, I started testing for Iodine/Iodide, and the level was zero. I started to add Seachem's Iodide supplement, a little at a time because I read that the level should be raised gradually. <Yes, correct> I started with .5 ml daily, and worked up to now 2 ml per day for the last several days added in my RO makeup water. I still am not getting a reading with the test kit, (but the reference sample included in the kit is right on the money). So it would seem that all the iodide I am adding to the tank is going somewhere faster than I am adding it. <Hmm, it's possible... but would test the stock solution and test kit together by making a bit of water and it together and testing immediately...> I have read in your faq on iodine that you suggest 10 drops weekly, <Depends on strength/concentration of stock solution, type of gear, livestock... of course> which is far less than I am putting in daily. I have two Skilter 250's on the tank, with one bag of Seachem Purigen in one of them. Could the Purigen be removing the Iodide from the system?  <Ah! Yes, this is possible> How much do you think I could be safely adding without it becoming toxic in the initial rush? <Let's send this off to the fine folks at SeaChem (I'll cc them). I would remove the chemical filtrant, try on the low dosage side (2 ml. per twenty gallons) again till you get a reading that and the next day.> Thanks for your insight on this, and for all the information you have provided on the WWM web site. Bob Dundon <Thank you my friend, for contributing to same. Bob Fenner>

Re: Iodine level question >I have read in your faq on iodine that you suggest 10 drops weekly, ><Depends on strength/concentration of stock solution, type of gear, livestock... of course> >which is far less than I am putting in daily. >I have two Skilter 250's on the tank, with one bag of Seachem Purigen in one >of them. Could the Purigen be removing the Iodide from the system? ><Ah! Yes, this is possible> No, Purigen won't remove the iodide any more than it would remove the chloride in the water. However, iodide is utilized rapidly but it is also depleted rapidly chemically via oxidation to iodate. Iodate can in turn oxidize iodide to iodine which will be slowly depleted by gassing off. Iodine in turn can be reduced to iodide. We stabilize Reef Iodide with reducing agents to keep it stable in the bottle and to extend its effectiveness in the water after use. One could extend its useful life somewhat by using a water conditioner such as Prime that contains reducing agents (normally used to reduce chlorine to chloride, in this case to reduce iodine to iodide and prevent iodate formation). However it's hard to say how much would be needed and for how long the life would be extended as this depends on numerous variables in the tank. >How much do you think I could be safely adding without it becoming toxic in  the initial rush? ><Let's send this off to the fine folks at SeaChem (I'll cc them). I would remove the chemical filtrant, try on the low dosage side (2 ml. per twenty gallons) again till you get a reading that and the next day.> Yes, this makes sense and is what we would recommend as well. You don't need to remove the Purigen however. I'd also recommend testing say, 10 or 20 minutes after dosing so you can prove to yourself that it is there right away, but then is being slowly used and depleted throughout the day. BTW, what is the url of your website that the other gentleman referred to? <WetWebMedia.com, thank you for this input. Bob Fenner> Seachem Laboratories, Inc. www.seachem.com 888-SEACHEM

Overdosed with Potassium Iodide Bob, Yesterday I mistakenly over dosed my 65g system with 1/2 teaspoon of pure potassium iodide. <Yeeikes!> After I realized it, I immediately did a 50% water change, however the system still smell like medicine cabinet, and all fishes and corals are looking sick. Is there a quick way to neutralized the potassium iodide other than doing the water changes? <Yes. Please immediately add about half a pound of activated carbon in your filter flow path... and/or a unit of PolyFilter...> As always appreciates your quick response and help. Thanks Wayne <Be ready to move, remove organisms if/when they die. Bob Fenner>

- Removing Excess Iodine - Dear Folks, <Good morning, JasonC here...> I believe I have overdosed my tank with an iodine additive.  I had a brand new test for it, which kept telling me I had none at all.  Finally realized the test was wrong and the levels were sky-high. <Oh my...> I have lost several clams and a zoanthid colony.  My question is this:  Other than water changes and carbon is there any way to remove the offending element quickly? <If you have an efficient protein skimmer the iodine will get blown out fairly quickly - within a week.> I have been doing water changes and carbon replacements every other day for over a month and the levels still seem to be high (got another test, duh).  I thought iodine was supposed to deplete quickly, but it's been six weeks! <Then something is wrong with your test kit(s). Iodine is reactive enough that the carbon and water changes should have eliminated it quite a while ago.> Any advice you could give me, other than quit dosing the tank, would be appreciated. <Well... stopping the dosing will help too, but do check with the folks where you obtained your test kit - something seems wrong with either the kit or your methodology.> Thanks!  Pam <Cheers, J -- >

Iodine Deficiency? Hi all! <Hi there! Scott F. with you today!> I have a question about iodine and shrimp!  I have a pair of scarlet cleaners and at their last molt they seemed to have some trouble and one of them now has crooked antennae and weak joints (they seem to bend just because of his weight, it's not normal at all)  This is the first time their molts have gone bad and I just recently added new lights so of course the algae is growing more.  So could the growth of the additional algae have soaked up all the iodine?  That's all I could come up with for the problem because I've had both these shrimp for several months and they've never had problems. <Interesting theory; unusual, but I suppose, possible.> I add calcium twice a week so I don't think they're calcium deficient. <My easy solution to the possible iodine problem is to test for it. If you do find it a bit low, you can address the problem with regular water changes (which will replenish this and other beneficial compounds), or, if absolutely necessary- with iodine supplements. Remember to test for anything that you intend to add to the tank, okay?> And one other thing, some of the house plants I keep are showing necrosis of the leaf tips because of the fluoride in the city water, could too much fluoride be causing the shrimps' problems too? <I really don't know- I suppose that is possible, but I'm leaning towards your iodine theory> My LFS suggested buying "Reef Evolutions" Potassium Iodide concentrate and adding it regularly. will this do the trick if Iodine is the problem?   <It will, but again- I implore you to test before adding any kind of supplement to the system> So many questions!  At the very least I can say I've never learned so much from a hobby as I've learned from keeping saltwater. <It keeps you on your toes, huh?> Crazy, confusing, amazing, beautiful stuff. <Great description of the hobby, huh? Highly accurate, though!> Thanks for your help, I really appreciate all the time you guys put into helping out the little people (and their little pets)  Have a fantastic week! Rachael <Well, I'd like to thank the Academy, my agent, the manufacturers of Tropic Marin...Seriously- we are happy to be here for you. I'm a hobbyist, just like you. We learn as much as you do every day! Good luck! Regards, Scott F>

Where does all the iodine go Hi, <Hi Nate, Adam here today.> In browsing your FAQs, I came across a number of statements that iodine disappears from an aquarium very rapidly, maybe lasting only 6 hours.  Where does the iodine go--is it absorbed by critters, precipitate out of solution, "broken down" by the skimmer. <Hmmm.. "broken down" may be a poor choice of terminology.  Iodine changes form, binds to organics and is absorbed by organisms (particularly algaes).  That which is bound to organics may then be exported by the skimmer.  Also, depending on the chemical form it takes or if it binds to organics, the iodine may be present but not detectible by a standard test kit.> Even assuming daily doses, how can the denizens of a home reef system get enough iodine if it is only present 1/4 of the time (6 hours out of every 24)? <Well....  It really isn't gone, and even if it was, most critters get quite a bit (enough to meet their needs in most cases) through food.> Also, how does iodine in the ocean stay in a useable state? <Again, different forms can be taken up by different organisms and the iodine then enters the food chain.  Also, the ocean represents such a vast pool of any of the elements it contains, the concentrations rarely change.> One last question--is it worth it to dose strontium or magnesium--or should I simply rely on regular water changes? <Water changes probably will meet these needs in most cases.  I would suggest testing for either before adding.  The range of opinions on Sr ranges from poison to mandatory.  I no longer add it, and don't think it has made a difference.> Thanks Nate Terry <No worries!  Adam>

Iodine causing Xenia problems? Hey Crew, I had a problem with my red soft corals losing some of their color. My LFS sold me Lugol's iodine and I starting with very small amounts increasing to one drop a day four times a week (90 gallon tank). But now my once thriving pulsing Xenia are not looking so good. << Really?  They usually do better with Iodine.  I would do a water change and stop adding Lugol's for a while. >> It looks like some one let the air out of them. I stopped using the Lugol's and they are starting to look a little better. Do you think this was the problem. I thought Xenia love Iodine? << Yes, but maybe you have over-dosed the tank.  It is toxic at high enough levels. >> or should I be using a different produce maybe one that has Iodide? << No, don't try more chemicals. >> Also I had a problem with my skimmer. After reading your site for two hours I stumbled onto someone with a similar problem as myself. I have an over flow box with a few return jets up high for surface current. After bringing those down a bit my skimmer seems to be working more efficiently. Do you think this is the right move? << Hey if it is working better, then I guess so. >> Every time I see someone else's tank they seem to have a lot of surface current. Thanks again for all the free advise. If you ever decided to charge for this site. I would be the first on line. <<  Blundell  >> Iodine depletion in my system  12/22/05 Thanks in advance. I have a 12 gal setup w/a fuge in the smallish sump. I'm running the lighting for the fuge opposite of the display lighting. I have a baseball sized clump of Gracilaria for the fuge. I have a great growth of coralline in the display which is encrusting everything. My question is does red macro use a lot of iodine? <No> In this 12gal tank there is only actually 7 gal of SW after LR and LS displacement. I do a 21 oz wc daily except on sat and sun. The question stems from getting loads of different advice and when told I did the daily wc's the majority opinion was not to supplement w/ the Kent's iodine. I had been before and my skunk molted on several occasions w/out a hitch. I introduced a peppermint and stopped the supplementing of iodine. 6 days later when he attempted to molt, he was DOA. I've read that w/the Kent's or SeaChem's potassium iodine is so diluted that it shouldn't hurt the system. Can someone give me a definitive answer. <I believe it is better to dose than not.  I use the Sea Chem product myself on a weekly basis.  The iodide/iodine definitely helps with the molting process. I'll paste a email I received from SeaChem a while back regarding this.> "Our Iodide is stabilized as Iodide and therefore it is less harmful than Lugol's.  However we do still recommend to use a test kit when dosing a Iodide supplement (any supplement to be exact).  If a person does not want to test iodide they can still get some through the use of Reef Plus twice a week.  This dosage is minimal and even with few to no iodide absorbing animals the iodide level stays low." Best Regards, Seachem Tech Support~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Thanks, Mike. <You're welcome.  James (Salty Dog)>  

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