With his permission, I post below a message from Scott at SpectraPure. He doesn't want to get into an argument over this, but I feel this is an important issue in terms of using testing services. When I sent my sample tank water, I also sent samples of my RO/DI water which I have posted earlier. There were some surprises so I forwarded the results to Scott. Here is his reply:
Jonathan,
Thank you for the test report. This is not the first we have received from AWT. We have started a collection.
Our only comment is that, while some of the numbers individually are believable, when you add them up, you get 141.8 PPM of "stuff" in your water.
I don't think you believe that there could be so much stuff in the DI water! A look at the magnesium value of 139 PPM makes it is hard to take the rest seriously. Even the remainder of 2.8 PPM is more that we typically measure out of a DI cartridge. We would have to question the methodogy of the individual tests, and ask are they using equipment explicitly suited to low-conductivity water, or are they using tests more suited to seawater. What are their measurable minimums for each element?
More to the point, how is your tank doing? Diatoms, hair algae, etc.?
So obviously AWT is not advertising that they test low conductivity water and that should be very clear as far as I am concerned, but Scott's response basically sheds some light on water testing in general.