I'd show the equations, but I'm poor at ASCII art.
In this case, a good portion of the EDTA (which is a pain to dissolve and
somewhat expensive) is simply allowing you to substitute FeOx for Oxalic
Acid.
Tox
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*  Tox Gunn .......tox@remarque.berkeley.edu  *
*  "Your sanity is not my responsibility!"    *
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