just an update to this thread. i installed a dual inline tds meter and recalibrated it to 10% below the 342 ppm stock solution as directed by the manufacturer. my original tds from the tap was 340ppm. this was taken on a handheld tds meter of unknown calibration when i started this thread. dial ahead till now and the tds post water softener is 160 ppm and is 0 ppm after the rodi. i believe this whole time i was getting incorrect readings from a poorly calibrated meter. buy your own test equipment kids!