# EC

> EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.

- Canonical: https://genetixbay.com/knowledge/glossary/ec.html
- Also written: electrical conductivity, conductivity, EC reading, nutrient strength, electroconductivity
- 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"

EC (electrical conductivity) is the ability of a solution to carry an electric current, which rises with the concentration of dissolved ions. Pure water conducts almost nothing; nutrient salts dissociate into charged ions that conduct. EC tells you the total salt strength of a solution, not which ions are present: a solution of table salt and a balanced nutrient mix can share the same EC.

## In practice

Typical working ranges for the input solution:

| Stage | EC ([mS/cm](https://genetixbay.com/knowledge/glossary/ms-cm.md)) |
|---|---|
| Seedlings, clones | 0.4–0.8 |
| Early veg | 0.8–1.2 |
| Late veg | 1.2–1.6 |
| Flower | 1.4–2.2 |

More is not better. Hershkowitz, Westmoreland and Bugbee (2025) found elevated root-zone nutrient concentration did not increase yield or [cannabinoids](https://genetixbay.com/knowledge/glossary/cannabinoid.md) in medical cannabis, while Baas and Wijnen (2023) tested cannabis across EC 1.8–12 mS/cm in rockwool. Too high an EC causes [osmotic stress](https://genetixbay.com/knowledge/glossary/osmotic-stress.md) and tip burn. Always note your base water EC; tap water often starts at 0.2–0.8 mS/cm.

## Units and formula

1 mS/cm = 1,000 µS/cm = 1 dS/m = 10 CF ≈ 500 ppm ([500 scale](https://genetixbay.com/knowledge/glossary/ppm500.md)) ≈ 700 ppm ([700 scale](https://genetixbay.com/knowledge/glossary/ppm700.md)). EC rises about 2% per °C, so meters report at 25 °C.

## Don't confuse with

- **TDS/ppm**: a number calculated from EC with a [conversion factor](https://genetixbay.com/knowledge/glossary/conversion-factor.md); EC is the actual measurement.
- **Runoff EC**: what leaves the pot, not what goes in.

## Related terms

[mS/cm](https://genetixbay.com/knowledge/glossary/ms-cm.md), [ppm500](https://genetixbay.com/knowledge/glossary/ppm500.md), [ppm700](https://genetixbay.com/knowledge/glossary/ppm700.md), [TDS](https://genetixbay.com/knowledge/glossary/tds.md), [Runoff EC](https://genetixbay.com/knowledge/glossary/runoff-ec.md), [EC meter](https://genetixbay.com/knowledge/glossary/ec-meter.md)

## Read more

- [EC vs PPM: the 500 and 700 scales, CF, and how to convert](https://genetixbay.com/knowledge/ph-ec/ec-ppm-scales.md)
- [Building a cannabis feed by stage: ppm targets per element and how to hit them](https://genetixbay.com/knowledge/nutrients/feed-by-stage.md)

## Sources

1. Hershkowitz JA, Westmoreland FM, Bugbee B. 2025. Elevated root-zone P and nutrient concentration do not increase yield or cannabinoids in medical cannabis. Frontiers in Plant Science 16:1433985. https://doi.org/10.3389/fpls.2025.1433985
2. Baas R, Wijnen D. 2023. Effects of EC on cannabis in rockwool (1.8 to 12 mS/cm). Acta Horticulturae 1377. https://www.ishs.org/ishs-article/1377_97
3. 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