TL;DR: Press and hold the CAL button for 5 seconds while the probe is submerged in the pH 7 buffer solution. When it flashes three times, calibration is complete.
What you need
Your pH meter and a pH 7 buffer solution. These solutions can be found online, in hardware stores or aquarium stores. For most home hydroponic setups, calibrating to pH 7 is accurate enough. For more precise calibration you can also calibrate to pH 4.0 and pH 9.18, but this is not required for typical home use.
Step by step
- Pour the pH 7 buffer solution into a small container. Make sure there is enough to fully submerge the probe.
- Place the probe in the solution.
- Press and hold CAL for 5 seconds. The display will flash three times when calibration is complete.
- Rinse the probe with clean water.
- Discard the used buffer solution. Once used, it cannot be reused for calibration.
A note on the buffer solution
Keep unused buffer solution stored separately and sealed. Once exposed, it degrades and will no longer give accurate calibration results.
Apr 29, 2026