Understanding EC & Nutrient Strength: A Grower’s GuideUpdated 2 days ago
🌱 Summary
Electrical Conductivity (EC) and Parts Per Million (PPM) measure how “strong” your nutrient solution is.
This guide explains what EC & PPM really mean, how to convert between them, ideal ranges for different plant stages, and how nutrient strength affects plant uptake, growth, and risk of burn.
⚡ What Are EC & PPM?
EC (Electrical Conductivity) measures how well a solution conducts electricity. In practical terms, that’s how many dissolved ions (nutrients, salts) are in your solution.
PPM (Parts Per Million) is a converted measurement that estimates how many milligrams of dissolved solids exist per liter or gallon.
EC is a direct measurement; PPM is a derived number based on EC using conversion scales. THCFarmer - Cannabis Cultivation Network+2wiki-science.blog+2
Note: There is no universal PPM scale — some meters use 500 (NaCl basis), others 700 (KCl basis), and the actual conversion depends on the specific salts in your mix. wiki-science.blog+1
🧮 How to Convert EC ↔ PPM
If your meter reads EC, you can approximate PPM via:
PPM (500 scale) = EC × 500
PPM (700 scale) = EC × 700 wiki-science.blog+2THCFarmer - Cannabis Cultivation Network+2
Because different meters use different scales, two growers measuring the same mix may get different PPM values even though EC is the same. That’s why many advanced growers prefer sticking to EC. Zamnesia+1
🌿 Why Nutrient Strength Matters
Underfeeding (Low EC/PPM): Plants don’t receive enough nutrients → pale leaves, slow growth, stunted yields.
Overfeeding (High EC/PPM): Salt buildup and nutrient burn can damage roots, cause leaf tip burn, lockouts.
Stage-based Needs: Plants require different strengths at different stages (seedling, veg, bloom) — your EC target should reflect that. Zamnesia+2MistCulture+2
Water Loss Effects: As plants use water, the nutrient concentration increases (EC rises), so runoff and dilution matter. Coco For Cannabis
📊 Sample EC Ranges for Grow Stages (Cannabis / General)
These are general guidelines. Always start on the lower end and adjust based on your plant’s response:
| Stage | EC (mS/cm) | Approx. PPM 500 scale |
|---|---|---|
| Seedling | 0.4 – 0.8 | 200 – 400 |
| Vegetative | 1.2 – 1.8 | 600 – 900 |
| Flower / Bloom | 1.8 – 2.4 | 900 – 1,200 |
| Late Flower / Flush | 0.8 – 1.2 | 400 – 600 |
These match ranges seen in cannabis-specific guides. Zamnesia+2Coco For Cannabis+2
🛠️ How to Measure & Use EC in the Grow
Tools You Need
EC or Conductivity Meter (often combined with pH in combo meters)
Calibration solution to keep it accurate
Best Practices
Calibrate meter regularly (weekly).
Measure both inflow and runoff (especially in coco or soil) — the runoff EC reflects what roots are exposed to. Coco For Cannabis
Adjust nutrient strength by dilution or concentration — don’t jump large steps.
Watch for signs of stress — “ideal” numbers are guidelines, not absolutes.
🔄 Linking EC With Other KB Topics
EC & pH Interaction: Even perfect EC doesn’t matter if pH is off — nutrients become unavailable.
Nutrient Strength & Feeding Charts: Your Cronk feed charts should correlate with EC/PPM ranges.
Additives & Boosters (e.g. CalMag, Sticky Bandit): Be aware how adding them shifts EC and mineral balance slightly.
🌼 In Summary
EC and PPM are your best tools for monitoring nutrient strength.
Master them, stay in your plant’s “sweet spot,” and adjust gradually.
Over time, your plants will respond — healthier growth, fewer deficiencies, and better yields.
🧩 Related Articles
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