anything over 15ppm has caused me problems,even if it is just
slight spotting.
night falls earlier now so will be strong possibility any mistakes
are covered up.

my personal feeling is if your intial cleans over the first few months
are done with oooppm and all ingrained dirt has been pulled out
of frames etc,on 4 weekly maintenance cleans you will get no
or minimal problems from a slightly higher tds
my tap water measures 58ppm and there is no way i would use
it,i tried on my own windows and it left a right mess