Dual TDS meter placement

[MRRBW]

I have a quick question about a dual tds I just purchased, should it be placed pre-system (from water outlet) and then exit RODI line or should I place it pre - ro membrane to watch for di resin life and then post ro membrane?
what is the standard?

thanks for the guidance in advance!

 

[Reefer5640]

I think it’s preference really. I have a triple and I have them on my incoming, post RO membrane, and post DI canister. If I had to pick two of the three I guess I would go post RO membrane and post DI canister and possibly add a tee with a cap/plug to check incoming with one of the two probes if I were to ever suspect a shift in my incoming water. I guess it depends on how consistent the TDS of your water supply is. Mine is pretty consistently at ~300 so for me I want to monitor my filter life/performance. Elevated TDS on “post RO membrane” tells me to replace one of my filters if they go prematurely.

 

[mann1139]

Agree with Reefer. You can put it 'upstream', but the two measurements that matter most are what is coming out of the RO and what is coming out of the DI.