pH and EC for Beginners: The Two Meters You Cannot Skip
What pH and electroconductivity actually measure, the targets per crop, and how to calibrate the cheap meters that everyone owns.
Dr. Ramón Cienfuegos·April 25, 2026·9 min read
pH: the nutrient gatekeeper
pH controls which nutrients dissolve and which lock out. For most hydroponic crops, the sweet spot is 5.5–6.2. Iron, manganese, and zinc start vanishing above 6.5; calcium and magnesium drop out below 5.2.
EC: how much food is in the water
Electroconductivity (mS/cm) measures total dissolved salts — a proxy for nutrient strength. Lettuce: 0.8–1.2. Tomatoes in fruiting: 2.4–3.0. Always raise EC slowly: jumps shock the root zone.
Calibration isn't optional
Calibrate pH meters weekly with 4.0 and 7.0 buffer. Calibrate EC meters monthly with 1413 µS standard. An uncalibrated meter is worse than no meter at all.