# EC meter

> An EC meter measures how well a solution conducts electricity, giving nutrient strength in mS/cm or as ppm via a conversion factor.

- Canonical: https://genetixbay.com/knowledge/glossary/ec-meter.html
- Also written: EC pen, conductivity meter, TDS pen, ppm meter, EC tester, truncheon meter
- Glossary category: pH, EC and water · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

An EC meter applies an alternating voltage across two or four electrodes and measures the current, giving [electrical conductivity](https://genetixbay.com/knowledge/glossary/ec.md). Most include a temperature sensor and report EC at 25 °C. "[TDS](https://genetixbay.com/knowledge/glossary/tds.md)" or "ppm" meters are EC meters that multiply the result by a [conversion factor](https://genetixbay.com/knowledge/glossary/conversion-factor.md). Fixed "truncheon" style meters show EC on a scale of lights or markings.

## In practice

EC sensors are far more robust than [pH](https://genetixbay.com/knowledge/glossary/ph.md) probes: no glass bulb, no storage solution, and they hold calibration much longer. Calibrate every few weeks or after cleaning with a standard such as 1.413 [mS/cm](https://genetixbay.com/knowledge/glossary/ms-cm.md), and check against it if readings look odd.

Keep the electrodes clean. Rinse after use, and occasionally clean with mild soapy water or a dilute acid to remove [nutrient films](https://genetixbay.com/knowledge/glossary/nft.md). Make sure no air bubbles sit on the sensor face when reading, and stir gently.

Pick a meter that shows mS/cm, not only ppm, so your numbers translate to research and charts.

## Don't confuse with

- **pH meter**: measures acidity; different sensor, different care.
- **Substrate EC sensor**: inserted into the medium to read pore-water EC, often with moisture; values differ from [runoff](https://genetixbay.com/knowledge/glossary/runoff.md) EC.

## Related terms

[EC](https://genetixbay.com/knowledge/glossary/ec.md), [TDS](https://genetixbay.com/knowledge/glossary/tds.md), [Calibration solution](https://genetixbay.com/knowledge/glossary/calibration-solution.md), [ATC](https://genetixbay.com/knowledge/glossary/atc.md), [pH meter](https://genetixbay.com/knowledge/glossary/ph-meter.md)

## Read more

- [pH and EC meter calibration: buffers, slope, storage and when to replace a probe](https://genetixbay.com/knowledge/ph-ec/meter-calibration.md)
- [EC vs PPM: the 500 and 700 scales, CF, and how to convert](https://genetixbay.com/knowledge/ph-ec/ec-ppm-scales.md)

## Sources

1. Prasad L, Meehan M. Using electrical conductivity and total dissolved solids meters to field test water quality. NDSU Extension WQ1923 (rev. 2025). https://www.ndsu.edu/agriculture/extension/publications/using-electrical-conductivity-and-total-dissolved-solids-meters-field-test-water-quality