We recommend to always check the manual, but here are a few basics for calibrating an EC/TDS probe.
1. Start With The Basics
A clean and calibrated probe is the first step for obtaining accurate and repeatable results. When using a new probe (four ring probe), remove the rubber ring inside the sheath covering the internal sensor. Inspect the probe prior to use. For calibration steps for combination pH/EC probes, check out the pH Electrode Maintenance Guide. Rinse the probe with purified (deionized) water and use an extra rinse beaker with standard.
2. No Buffering Capacity
Remember that EC/TDS calibration standards have no buffering capacity sp they are easily contaminated. Try using a new/clean beaker with fresh standard as an additional rinse step before performing the calibration. This will help keep the standard for calibrating as free of contamination as possible. Also, calibrate from low concentration to high concentration and do not rinse with deionized water between standards.
3. Always Use Fresh Standards
Do not reuse standards. Again, the calibration standards are easily contaminated. Do not use expired standards. Once opened, the standards are stable for only 3 to 6 months.
4. Reference the Manual.
Some probes should have the standard stirring gently while calibrating. Check the manual for instructions on your probe.