Calibrating pH And EC Meters
Meters that have not been calibrated in a month can read half a point off, and a pH of 5.5 fed to indica seedlings in soil while the display says 6.3 produces lockout symptoms that look like a dozen things. Calibration solution costs little, takes two minutes and should happen before every batch of seeds goes in. Which meters hold calibration, which drift within days and how to store the probe wet are compared on https://kushindicaseeds.com. If the meter is the only thing you trust, verify it first.
