Dio,
How much Aquafina water did you use? I think this is your source. A
simple calculation to work out how much salt you added via the Aquafina
should suffice. Also, I think you'll be surprised by the (low) mass of
the crystals (you did say they were small). How big was the pot?
Also, was it salt, and not calcium carbonate (chalk)? Most of the waters
I've seen quote carbonate as being high on the list of ions present.
Calcium carbonate evaporated from water is usually a fine white powder.
(yes, I know it can get quite hard in a kettle, but it is usually a
powder first)
Richard