Dave- I think the 'uber' expensive stuff has labels like 'ultra pure' and goes beyond the so-called Grade or Type 1 Water; never tried it, b/c it is crazy expensive. (I think it may be used for injectable solutions, among other things). Yeah, they still require a business address- I used to use my law firm, which seemed to foreclose any question. I like your idea of using a TDS meter (which you mentioned in another thread), particularly if folks aren't pre-cleaning and rinsing records before putting them into the ultrasonic. I'm not surprised by the outcome of your experiments. For what it's worth, the pricing of some of this lab water is all over the map in the States, depending on the supplier and quantities--costs more for multiple smaller capacity bottles (obviously, just for packaging and handling) than larger quantities. I don't use enough of it to justify a water purification system. I think the better investment would be a small nuclear reactor in my backyard for cleaner power. Haven't checked government regulations on that front. Be well, :)
bill hart
bill hart