Why won't the Pocket Pro TDS Tester calibrate any more?
Pocket Pro TDS Tester will not calibrate
If the Pocket Pro TDS Tester will not calibrate. Verify that the standards are fresh and follow the calibration instructions correctly; if the unit will still not calibrate the Pocket Pro TDS tester needs to be replaced. The User Manual for the Low and High Range TDS Pocket Pro™ Testers contains calibration instructions.