I'm glad that my post yesterday about my conversation with Craig Bingman has helped to clear the iodine issue up.

I apologize for misleading the list when I wrote I2 <---> 2 I-, I should never have made two electrons magically appear. And I'm sorry that I didn't think of Iodate being formed (IO3-), but of course, I'm no Craig Bingman who studies such things for a living.

There was something else I kept trying to get through in my posts about the subject, but I'm not sure anyone read it. Hell, if I had no interest in Iodine, I'd have been deleting anything that said "Iodine" in the subject line too. (I got sneaky and changed the subject on this one.)

If you take a nice sterile beaker and add chemical A and B to the beaker, and A and B are known to react to form compound AB like this: A + B <---> AB. What you have is an easy to understand and measure reaction. You can easily test to see how much of A and B are left, and how much of AB was formed.

That's how you do an experiment in a laboratory. And for the majority of the reactions we talk about that happen in our reef tanks, if you isolate the compounds and put them in a beaker, they'd be extremely easy to measure. Most of them are ionic, the compounds are easy to test for, a lot of the reactions go to completion, and they're fast reactions. Not all of them, but many.

Now what happens in the reef tank is a completely different issue, because you have many different items that can also react with A, B, and C. I'm not talking about Boron and Carbon here, B and C are just letters for hypothetical chemicals.

For example, A + B <---> AB gets complicated in the reef tank if there is something around that is very similar to "A". For example, calcium, magnesium, and strontium are similar in the reactions they can undergo. So our reaction could change to:

Ca + B <---> CaB or Mg + B <---> MgB or Sr + B <---> SrB

Now lets say there's another chemical in our reef tank "D". "D" is very similar to "B", but reacts with chemicals that are like "A" much faster than "B" can, and if both "B" and "D" are present, you get a ratio of 25% AB and 75% AD. Now our reaction looks like this: (assume an excess of both B and D and sufficent "A" like chemicals to complete the reaction)

Ca + B + D <---> 25% CaB + 75% CaD Mg + B + D <---> 25% MgB + 75% MgD Sr + B + D <---> 25% SrB + 75% SrD

So now that we've added "D", things suddenly got a whole lot more complicated. You can easily imagine that if we started to consider other chemicals similar to the ones we're using, the reactions would get extremely complicated.

Then throw in the reactions that occur when our reef critters use up some of the chemicals, the pH shifts in our tank that can change equilibriums, enzymes that can take something and attach it to something else, the fact that we add trace elements through supplements and water changes, the waste products our critters produce naturally, and anything else I didn't think of, and it gets far more complicated than our orginal A + B <---> AB.

Our original reaction in a beaker was very simple. What I illustrated with the addition of new chemicals similar to the originals complicated everything immensely. The last set of reactions is much closer to what happens in a reef tank, but it still oversimplifies the truth.

Eric Edelman