Quick answer: Electrical conductivity, often shortened to EC, describes how readily water carries an electrical current. Dissolved ions increase conductivity, so EC is useful for tracking changes in dissolved ionic content.
Common units
EC is commonly displayed as microsiemens per centimeter (µS/cm) or millisiemens per centimeter (mS/cm). A value of 1.4 mS/cm equals 1,400 µS/cm. Record the unit every time; a number without a unit can be misread by a factor of 1,000.
What EC can and cannot tell you
EC is useful for tracking nutrient-solution strength, salinity trends, source-water changes, mixing consistency, and unexpected dilution or concentration. It does not identify which ions are present and does not replace laboratory analysis when the chemical composition matters.
Temperature compensation
Conductivity changes with temperature. Instruments may compensate readings to a reference temperature, commonly 25 °C, but the display and method should be checked. When comparing devices, use the same sample, temperature condition, unit, and compensation basis.
How to measure EC
- Mix the reservoir or sample consistently without introducing excessive bubbles.
- Rinse the probe and place it at the required depth.
- Allow temperature and the reading to stabilize.
- Record EC, unit, temperature, time, and recent additions or water loss.
Why EC changes
EC can rise when water evaporates or dissolved salts accumulate. It can fall after dilution or when a lower-EC source water is added. In hydroponics, plant uptake and reservoir management can change EC over time, but EC alone cannot show which nutrients were consumed.
Related Rovynel resources
Sources
Reviewed August 1, 2026. Educational content; application-specific targets should be confirmed for the actual system, crop, or aquatic species.