Parts Per Billion systems offer no noticeable real world advantage at all in a window cleaning environment - the whole PPB thing is a huge pile of steaming marketing BS. Here's why:
For the sake of simplicity I'm going to use round numbers in this explanation - but do the math with your own TDS readings and see for your self.
I have a 1000 litre static tank, a tap TDS of 300 and for the sake of math, lets say I use water at 001 (I always aim for 000).
So - 1000 litres = 1000,000 (1 million) milliliters - with water 1ml = 1gram, so 1000 litres of tap water contains 300grams of dissolved solids - of which my RO & DI remove 299 grams.
Keeping up so far?? Lets try that math with a system kicking out 1PPB:
My 1000 litre tank still contains 300grams of dissolved solids, the fancy new system now removes 299.999grams of dissolved solids - nearly a whole extra gram!!
So - the PPB system actually removes 0.333% (One third of one percent) more dissolved solids from my water - - instead of 1000x better its actually 0.00333x better.
It is however 1000x better at telling you when you need to change your filters - so consumables on these systems probably make their manufacturers more profit,..
I know the marketing says "1000x purer" which is (technically) correct - but Ionics infer that this makes it better for dirty jobs/first cleans, that it offers noticeably superior cleaning power and will give more consistent results than a PPM system - all of which is ridiculous.
Its like everyone complaining that its -20C outside & they cant work,.. I come along & say "Don't worry lads - I have a solution that will stop your water going below -19.7C,.. tomorrow you're going to earn at least £500!".
Bull poop - Ionics should be ashamed!