[DFliyerz]

Lately I've been messing around with electrolysis for fun, and in a recent experiment with iodized salt as the electrolyte, a copper wire and the anode, and a copper wire with aluminum foil on it as the cathode, I ended up with some brown residue on the bottom of the container. Logically, what might the residue be?

PS: I was not using distilled water, but instead regular tap water.

[Borek]

Copper (I) iodide comes to mind.

[billnotgatez]

I am not saying anything negative about your citizen science experiments
But
You have soup and reactive electrodes and you want to know the results of the electrolysis. That is a difficult request.

It is a good thing that @Borek has a quick mind.
I am just pointing out how difficult your question could be.


List of Contaminants and their (MCLs)
http://water.epa.gov/drink/contaminants/#List
WIKI Tap water
http://en.wikipedia.org/wiki/Tap_water

WIKI Iodised salt
http://en.wikipedia.org/wiki/Iodised_salt
Morton Iodized Salt: What’s In It?
http://www.wholelifeeating.com/2012/05/morton-iodized-salt-whats-in-it/

WIKI Copper(I) iodide
http://en.wikipedia.org/wiki/Copper%28I%29_iodide
Appearance White powder when impure: tan or brownish

[DFliyerz]

That sounds about right, thank you very much! I now know where I'll be coming for my other chemistry questions.