Here is Eric Bornemans reply to someone asking about additives on his RC forum. Iodine is towards the bottom. This is what I go by for what additives to add.
"There are MANY excellent books on this subject and it would be hard to recommend just one."
I disagree. I can't think of any that have good information on the subject.
"You may also want to post this on the "Chemistry" forum and see what Randy has to say?"
I think Randy will say that it few cases are there any good refrences to support or not support these additions.
" In general, these organisms need major as well as trace elements to grow & function just as any living organism does."
True, but which ones, how much, and in what form? Do they need to be supplemented? Seriously doubt it for most. Do they need to be removed from the tank because many are at levels that not only exceed NSW levels but could be compared to toxic spill event? Yes. See. Ron Shimak's articles at reefkeeping.com for more information - this is some of the first real information on these elements for aquariums.
"There are numerous reasons including, but not limited to, tissue production, Ca++ deposition, immunologic function, enzymatic reactions, photosynthesis, digestive function, respiration, reproduction, coloration, etc...etc... etc....etc..... "
True, but at the levels some of these are at, let's not forget reproductive sterility, direct poisoning, bleaching, tissue death, reduced growth, etc.
"This is a whole study in and of itself and I am sure that there are untold volumns dedicated to this very subject! "
For some, yes. For the ones metnioned, there is little to absolutely nothing on the subject.
"My advice would be before you add anything to your tank,test your water and see if you really need to add it.Search this and Dr.Ron's forum and after reading all that's avalable,make your decission.I never add anythind exept limewater for calcium and alk. "
Now there's some advice I like. Testing, adding what is needed and not what isn;t, and adding inthe form of foods, if anything.
"Good afternoon everyone, I've been looking around for a site or book that has additive information."
Good luck. Doesn;t exist, to my knowledge. I have lots of papers on the effects of tracers and major and minor elements, and grab them whenever I find them. But in terms of additives and most of the elements and direct studies, they are scanty to non-existent.
"I want to learn why corals need certain additives,"
Well, for starters, they don't.
" for example, why do we put molybdenum into our tanks?"
Because many years ago a few aquarium marketers said you should. And products were developed. And myths began.
" What does an animal do with it? "
Nothing - gnerally tries to get it out of its tissues as fast as possible.
"Strontuim, iodine, magnesium, etc.; what are they for?"
Fairly large volume of literature on strontium. Is used as a substitute for calcium. Lots of intersting information, but no reason you should need to add it...its not "required" - iodine is used in brown algae, vertebrates, antipatharians and some gorgonians. No evidnece at all to support its uptake or "requirement" in any other coral. Its "requirement" by direct addition to corals is also unknown. Magenesium is a major element in seawater and should be in the tankw ater in HUGE amounts and should never need adding by supplementation. Water changes should take care of this entirely.
"Can anybody recommend a book or site that has this info in terms I can understand? "
Unfortunately, no.
"
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Eric Borneman
