Iodine in 2026

[davidm777]

Hello,
My initial experience with Iodine has been this. I got some candy cane and duncans (among other corals) but these were not doing so great, specially the candy canes. I read somewhere candy canes are canaries on the coal mine for iodine.
I already had lugols but got the salifert iodine test kit. Measured and had undetectable readings. Added drop by drop and kept testing up to 5 drops when I thought it was ok (still below the range but detectable). By the next day it was back to undetectable. The candy cane did get puffier. So I kept adding lugol once a week.... until I just forgot to do it and the corals were fine. This weekend I saw the candy cane again a little shy and added Lugol so decided to revisit the subjet.
I read Randy's article from back 2003. Where he mentions the difficulties of measuring iodine with ICP but that was a while back. I found a more resent article of how to measure Iodine with Hanna and Red Sea reagents.... So now I am a little more confused than when I started hahaha. I know Randy had stopped dosing iodine and did not see any change on his corals.
My questions are, is Salifert still a valid test for Iodine?
Are there still chanllanges for ICPs to detect iodine levels. I know Randy had mentioned that some ICPs provide a reading that is of no help for aquaria. What is the level we are actualy after? I am just trying to understand the subject and the only article I found is kind of dated. I include the articles I am refering to for reference. Thank you in advance.


https://reefs.com/magazine/chemistry-and-the-aquarium-iodine-in-marine-aquaria-part-i/


https://www.reef2reef.com/ams/an-accurate-and-precise-method-for-measuring-iodine.909/

 

[Randy Holmes-Farley Verified Community Expert]

Icp- ms (say, by Oceamo) has no problem detecting seawater levels of iodine, but icp-OES does have some issues. If iodine quantitation is a significant goal, I’d use icp-ms.

Iodine rapidly depletes as algae and other organisms consume it.

Lugols is not just an iodine supplement, so folks attributing good or bad effects to it may be seeing things other than simple iodine supply issues. It can alter the chemical nature of other trace elements by reacting with them and altering their solubility and bioavailability/toxicity.

I recognize that you believe there is a benefit to dosing based on your experience, and that may be true, but I am somewhat skeptical of the utility of iodine dosing in many reef tanks (such as my old one where I dosed for years, then stopped and saw no apparent difference),