I changed out all my cartridges a couple weeks ago. DI went from 2 to 0. RO membrane was at 98% rejection.
This time, the DI unit was a color-changeable one. It is showing color change already about half-way up. And the TDS reads 3. Now the RO membrane reads 95% rejection. But even so, the DI should be able to handle that, no ??? :?
I should mention I left the flush valve open for some time and was running water.

Did this wreck my membrane....?
I've only used the TDS about nine times, it comes calibrated. Should it be calibrated already ?
Thanks for info...