[Amps] liquid cooled Amplifier coolant recommendations

[F. Veitch]

I am in the process of getting a water cooled GS-15B cavity on line and I
wonder if the group has any recommendations on coolants.  Distilled water is
typically of unknown provence, so you are never sure if it is really low
conductivity unless you measure it. Somehow the idea of 1700-2000V on water
of unknown conductivity just bothers me. (silly me!)  I have heard that some
Radar systems and high power lasers use a special ethylene glycol for a
coolant.  I wonder if anyone in the group has any experience with such
coolants and if they can recommend a source for same.

Thanks and regards 
Fletch 
K3JYD 
FM18