Hello.
Personally, I use tapwater (my house has a filtration system) and Hornady Case Cleaning Formula.
This is a concentrate, and I mix one capful with about 3 gallons of water; the instructions say 40:1 water to concentrate.
It is available from MidwayUSA (and other online suppliers), here :
http://www.midwayusa.com/product/71...ltrasonic-case-cleaning-solution-32-oz-liquid
I am not certain what is available in AUS.
I am also certain other cleaning solutions work, there are a couple of formulas for "make-it-yourself" cleaning solutions online, they just need some searching to find.
What kind of U/S cleaner are you using?