Tony
once resin tds starts to rise there isnt much you can do to stem the flow , maybe get an extra 1000 ltr or 2, but when its gone its gone.
I have tried all sorts of ways to get the resin to last longer as i have been di for nearly 3 years.
What i do is have one vessil on go until the tds rises above zero then i put fresh di vessil after the one which is rising.
So i have tapwater tds of about 80 going into vessil which is 5 approx and rising into fresh resin which comes out zero, when the first vessil gets to 80 ish i change it for fresh and put it after the last one i changed , if i have 2 vessils rising in tds together i put a third vessil in line.
Tried all sorts, nothing seams to help, i dont get stressed with it, if i start trying i am just wasting my time and time is more valuable than trying to get a few extra litres out of a bag of resin.
Dave