Naturally occurring iron readily precipitates out of the solution in aquaponic systems. As already stated, most of us use iron that is "held" in the water solution by a chelate or ligand... which is just a fancy word for something that keeps the iron molecule soluble and prevents the iron from reacting with other "stuff" in the solution. This is one of the main reasons why putting iron nails or whatever to rust in your system does not add adequate iron, if any, that is bioavailable.

Gel electrophoresis is a method where eletromagnetic fields are used to move DNA molecules through gel. So, we can assume such a field could interact with iron molecules and other compounds.

I'm not sure if the effect of an eletromagnetic field would do what you are saying, but eletromagnetic fields seem to effect the solubility of iron as well: http://www.op.titech.ac.jp/matgcoe/j/ne ... o%20rv.pdf

Food for thought. Interesting topic.