Nutrients
EC Calculator: Find Your Optimal Input EC and Drain EC
Select your growth stage, medium, and water EC — the calculator shows recommended input EC, max drain EC, and optimal pH range.
EC Calculator
Calculate Target EC
What Is EC?
EC (Electrical Conductivity) measures the electrical conductivity of your nutrient solution in millisiemens per centimetre (mS/cm). It serves as a proxy for total dissolved salt concentration — and therefore as the primary control parameter for nutrient delivery.
Too low and plants starve; too high and salt stress locks out nutrients. The sweet spot depends on growth stage, medium, and water quality.
Input EC vs. Drain EC
Input EC is the EC of your mixed feed solution. Drain EC (runoff) reveals salt buildup in the substrate. A drain EC 30–50% above input is normal. Values significantly higher signal salt accumulation — time to flush.
FAQ
Do I need to measure my tap water EC?
Yes. Base EC adds to your nutrients. Measure before every mix. Above 0.3 mS/cm, RO water is recommended.
Why are targets different for coco, soil, and hydro?
Coco has no CEC buffer, soil buffers nutrients, hydro provides direct root contact. Each medium requires different EC ranges to avoid over- or underfeeding.
What to do about high drain EC?
Flush with pH-adjusted water at half nutrient strength. In coco: maintain 20–30% runoff each feed. In soil: run a plain water feed every 2–3 cycles.