RODI not doing what it's supposed to!

[Ryanerickson]

I had a issue like this it ended up I had had di balls that was exhausted in my last pre filter but I figured it out by putting the line coming from tap directly into the ro then tested water that came out it was 0. What is the problem with di balls before ro? Will it make the life of my ro membrane shorter? I thought it would help it last longer because water coming out of pre filter is coming out at 1 ppm then it goes into ro any one know ? Thanks