That’s the best way to have them set up… after membrane and after di resin… tells you when the membrane is getting old and when to change di resin.So here's the deal. I bought a handheld TDS meter and tested my tap water. 52 ppm.
I then started looking at where the probes are connected to the RODI, and I found out the answer to why I was getting readings in position 1,2,3 of 1-0-0. There is no probe checking the incoming tap water. There is one after the RO, after the second DI, and then after the third DI (final water).
I called BRS and they said I could always move the them. I figured I would leave then where they are. I don't need to know what my tap water is as it is not being used for my tank.