Does anyone have a DI meter built into their RO/DI?

[craigwmiller]

I recently added a Dual Inline TDS meter to my system (previously using just a hand-held). I placed the two points after the RO membrane, and then after the DI.

The pre-filters don't really do much for TDS (which is measurement of much much smaller particles), leaving the membrane and DI resin doing the brunt of the work... Since DI resin is costly, knowing how efficient my RO membrane is operating is very important! I now can do a more serious flush of the membrane when the TDS post-RO is >5 TDS... and with the dual meter, I can quickly (seconds) have peace of mind that the post-DI water is still 0 TDS.


Using a hand-held checker getting measurements from the post-RO/pre-DI water is still totally possible - though somewhat tricky... It would take a Tee, check valve, and manual shutoff valve, letting you divert some water from the post-RO/pre-DI stream... you would need the check valve between the Tee and the DI though to ensure you don't get back-flush water from the DI into your Tee causing your reading to be skewed.