I don't remember where I read it, but I think it's actually not a good idea to use deionized water, at least with some metals. Because the water has no ions, it pulls them from the metal, causing corrosion. I don' t think ionized water is more corrosive than deionized. I personally only used distilled water with anticorrives and algicide.
After a very quick Google search,
I found a short webpage that describes the reasoning. A little more time should probably find more/better explainations.