Hello,
It doesn't matter what grade of fertilizer is used. The most efficient policy is to obtain the salts at the lowest price possible.
It also doesn't matter whether salts are dissolved in distilled water or tap water or lake water or Nile River water. Again, the most efficient policy is to use the least expensive water. The only caveat is, for example, if the tap contains toxic substances such as pesticides or herbicides, or is high in pathogen count. Dechlorination is not a concern because it is easily done. In fact the amounts added to the tank will be very small and the chlorine in the small bottle will suppress fungal growth and so forth.
Cheers,