Steven youre right on opening a can of worms
http://www.thereeftank.com/ubb/smile.gif Iodine is another one of the wholly grails of reefing. Those who dont use it and do fine think its not needed and those who do and get away with it rave about it and swear by it. A couple thoughts here> I dont normally dose Iodine, however I have used it in small batches after proping corals as it is a Strong Antiseptic. For the most part I gree with the theory you will get all the Iodine needed through water changes and additions of food.
The problem is further compounded by the fact that Iodine is hard to test levels for in an aquarium with the test kits available to the hobby. They are marginal at best and Iodine in seawater converts to iodide and iodate, different compounds that have different effects on marine organisms. I will be the first to admit I'm not a chemist so Horge or Tom Wyatt feel free to jump in and bail me out here
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I'm taking the liberty to cut and paste an email reply Alice got from Eric Borneman on the question of Iodine as well as other trace elements. To the best of my knowledge Eric, Ron Shimek, Craig Bingham as well as the other marine biologists downplay the addition of Iodine and the other trace elements. Erics quote is as follows:
Hi Alice:
Yes, I'll be at MACNA, though primarily for the diving and research
opportunity, not the event. Feel free to post my response below
___.
Council uses the argument that since its (Sr) abundant, it must be necessary
and also therefore that supplementation is necessary. This argument is
invalid. Is anyone dosing sodium? Testing for chloride ion? And these
actually do have value!
There also seems to still be an aquarist notion that the "jury" is out on
trace and minor element supplementation. Well, only so long as ignornace is
bliss and aquarists continue to use aquarium literature to "know." Knowing
means reading critically, and knowing enough to assess real from myth.
Strontium is not necessary for coral growth or health. It is used in
skeletogenesis, but it is not required for skeletogenesis. Radium, Uranium,
chitin, organic complexes and other associated "garbage" are also accreted
into
coral skeleton as the coral attempts to either move these out of its
tissues, or as non-specific inclusions. There are some anamolies...like why
P. damicornis incorporates a higher percentage of chitin in its matrix than
other corals seem to. But, there is no evidence whatsoever of any coral
requiring strontium for any purpose whatsoever. There are possible, though
conflictory, temperature related and seasonal related changes in Sr
incorporation, but nothing that suggests it is used for any purpose other
than calcium substitution. Even the one reference that suggests possible use
of smaller divalent ions for nucleation catalysis are feeble, at best.
Corals grow just as quickly and are just as healthy in its absence.
Iodine...well, it is required by some animals. Fish, for example - By diet,
though, not osmosis from the water column. In corals, iodine can be found in
high amounts in the central chord of some gorgonians and antipatharians,
primarily from deep water. No evidence to suggest why, its need or
requirement, or what the effects of depletion are. Other corals? Not a
shred of evidence that it is used for any reason at all. They obviously do
fine without supplementation, and I would suggest using dulse flakes or other
dietary derived iodine sources for those other organisms which may require
it.
As for the whole skimmer part of this thread, the use of a skimmer, depending
on individual situations and preferences, may or may not be necessary.
Certainly all my tanks have done just fine without skimming for years.
However, there may be cases where they are needed or desirable. As for what
is removed? Coral food, that's what. ALL corals use dissolved organic
material significantly in uptake as a nutrient source...also
bacterioplankton, and whatever is alive in the water column, including
detritus (particulate organic material). What you remove is food for
sponges, corals, tunicates, bivalves, etc. If your water quality management
doesn't allow for high quality water without skimming, tis better to skim,
without question.
As for phytoplankton, this phytoplankton kick is both a blessing and a curse.
Clearly phytoplankton availability is desirable in that it provides limtied
food for some filter feeders, and also food for the small worms and
crustacea which, in turn, provide real zooplantkon-type food for other
animals. However, and despite some usage by various soft corals,
stony corals
don't really eat phytoplantkon. One has only to look at their cnidom and
lack of filtering appendages to indicate their prey sources. Soft corals
have some herbivorous tendencies, but most will get more nutrition,
especially nitrogen, from consuming other material. Herbivorous species of
Dendronephthya and certain other genera being exceptions. Directly attending
to the production of zooplankton within the tank or through addition of daily
Artemia nauplii will, IMO, be more beneficial that buying all these dead
greenwater products. Culturing Nannochloropsis is so easy, too, and better
than buying these off the shelf products.
Anyway, I'm finished with the tome, now. Be good
eric
Sorry it might be hard to read without seeing the whole context, ask ALICE, I think she'll know
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Reef as if your life depended on it, yours might but the sea's does
Doug moderator TheReefTank
