Good point. In my case, I dose Iodide and test for Iodide. The Salifert test kit can test a few different forms, but like you said, you need to know which to test for. To your point, if you’re dosing and not testing for the correct form of Iodine, you could easily overdose.
I have two “vivid rainbow” colonies. One I highly trust the source, the other is also trustworthy but doesn’t remember where it came from. From the trusted source, the colony is beautiful. From the other, it is brown. When I first got it, it looked exactly like the “trusted” colony. And they are in the same tank right next to each other. So I’d say there is merit to your theory.This is going to totally be way off in left field, but... I have always wondered if there are more than one "strain" of this going around. I have never cared for it enough to get it from somebody who I know got it from Vivid with a good lineage, so I wonder if the less colorful version that people struggle with is just a bad look-alike? I am nearly positive that this happens with Forest Fire Digi in my area - everybody has it, but I think that everybody has a fake since nearly none of it gets green underneath. There are a LOT of fake Pearlberry corals.
