Many cultivation problems do not depend on fertilizers, but on instruments that measure incorrectly.
pH and EC probes should be calibrated regularly because, over time, they can lose precision. Even a deviation of a few tenths of a pH can reduce nutrient absorption, causing deficiencies or nutrient lockouts. Similarly, an uncalibrated EC meter can lead us to fertilize too much or too little.

When to calibrate?

• Before first use.
• Every 2-4 weeks (or more often if used frequently).
• After long periods of disuse.
• If measurements seem unusual or inconsistent.

Also remember to always rinse the probe with distilled water after use and, for pH, to store it in the appropriate storage solution: letting it dry reduces its precision and can damage the sensor.

A calibration takes only a few minutes, but can prevent weeks of plant problems.

I can only agree with you! I also recalibrate my tester every 14 days or so.

I calibrate every 2-3 weeks as well.