Mushrooms and Iodide

use Kent Tech-I its safer does a dispersal over time. i rarely check it and i dose once a week and its all fine so check it out. but if u use iodide or lugals id test for it regularly. it can sneak up on u.

Possibly you had enough to cause the shrooms to go into survival mode. The reproduction may have been it's way to increase the chances of survival of the species. Much like a clam that is stressed goes into spawn mode sometimes.

I certainly don't have a definitive answer for you but I know I would never dose anything that I haven't tested for and found to be deficient.
FWIW, in 13 years of reef keeping, I've never dosed trace elements or iodine to my tanks.
Normal water changes should take care of the needs, but also, pretty well all foods have forms of iodine and trace elements in them so as long as you feed your tanks, you are also adding iodine and trace that way.
Iodine, like anything, must be used with caution as it can poison your tank if you use too much.
Randy Holmes-Farley from RC does not recommend dosing iodine under normal circumstances.
For anything chemical related to the hobby, see his sticky about "Reef Chemistry" at the top of his forum on RC.
This reef chemistry article sticky is the most important page on the internet for me. There is just so much excellent information contained in the many links it has.
REEF CHEMISTRY ARTICLES

I actually raised similar question about a month ago. Some of my corals literally all of sudden started to die once I started dosing iodine. It seems that there's quite a bit of controversy out there regarding whether or not you even need iodine in reef tank.. and if it can actually hurt your corals. I believe that my mistake may have been overdose. Those supplements out there (I heard) are pretty concentrated and a small overdose (even couple drops) can lead to pretty big change in the water chemistry. But then again... everything I'm saying right now are "I heard" statements based on some research. I haven't found ground to agree or disagree with any of these statements as there are so many different arguments. After my horrific experience with the iodine, I stopped dosing it, and everything seems to be normal again.

I guess we will never know what happened to my tank... if the failure of my corals were truly due to iodine. All I know is that there are plenty of very successful reef tanks out there that never dosed iodine, and until anything is further proven, I plan to stay away from it.

Sorry that none of what i said answered your question. Just wanted to tell you little bit of my personal experience.