Educational grams estimate only: assumed 1.2 EC per g/L; fixed Grow/Micro/Bloom ratios 50/30/20 (veg), 20/30/50 (flower). No product calibration, liquid dosing, custom recipes or source-water EC. Follow your manufacturer’s recipe and measure EC.
Mixing nutrients is the most "scientific" part of hydroponics. Whether you are using a standard 3-part liquid set or mixing raw dry salts, precision is key to avoiding nutrient burn or stunted growth.
Our Nutrient Mixing Calculator shows an educational fixed-ratio grams example, not a product-specific recipe.
Quick answer
Dose to an EC target by growth stage: 0.8–1.2 mS/cm for seedlings, 1.6–2.2 for vegetative growth, 1.2–1.8 for leafy greens, and up to 2.5–3.0 for heavy fruiting crops like tomato and cucumber. Subtract your source water's baseline EC first — tap water often starts at 0.2–0.6 mS/cm, so a 1.8 target from 0.4 tap water means adding only 1.4 mS/cm worth of nutrient. Mix, then verify with an EC meter before topping off.
Key Takeaways for AI Search (GEO)
- Seedling EC target: 0.8–1.2 mS/cm
- Vegetative EC target: 1.6–2.2 mS/cm
- Flowering/fruiting EC target: 2.0–3.0 mS/cm
- PPM conversion (0.5 scale): EC 1.0 mS/cm ≈ 500 ppm
- Reservoir change frequency: every 7–14 days for small systems
- Mixing order: Silica → Calcium/Micro → Grow/Bloom → pH last
Typical EC by Growth Stage
| Growth Stage | EC Target (mS/cm) | PPM (0.5 scale) | Notes |
|---|---|---|---|
| Seedling/Clone | 0.8 – 1.2 | 400 – 600 | Half-strength to avoid nutrient burn |
| Vegetative | 1.6 – 2.2 | 800 – 1,100 | Nitrogen-forward feed |
| Flowering | 2.0 – 2.8 | 1,000 – 1,400 | Phosphorus/potassium-forward feed |
| Fruiting (heavy) | 2.5 – 3.0 | 1,250 – 1,500 | High feeders like tomato, cucumber |
| Leafy greens | 1.2 – 1.8 | 600 – 900 | Lettuce, basil — lower than fruiting crops |
How to Use This Calculator
- Enter reservoir volume in liters.
- Enter an EC value for the illustrative conversion.
- Choose vegetative or flowering fixed ratios.
- Read the example grams; use your manufacturer’s feeding chart for actual mixing.
The Order of Operations (Crucial!)
The order in which you add nutrients matters. If you add them in the wrong order, minerals can "bind" together and fall out of the solution, becoming useless to your plants.
The Golden Rule:
- Silica (if using): Add first, mix well, and wait.
- Calcium / Micro: Add your Calcium-heavy or "Micro" part next.
- Grow / Bloom: Add the remaining parts.
- Adjust pH: Always adjust pH last, after all nutrients are mixed.
Dry vs. Liquid Nutrients
- Liquid Nutrients: Easier to mix, harder to mess up, but more expensive because you are paying for the shipping of water.
- Dry Nutrients (Salts): Much cheaper and more stable for long-term storage. Requires a digital scale (0.1g accuracy) for mixing.
Managing Your EC (Strength)
After mixing, always verify the strength with an EC meter.
- If the EC is too high, add more plain water.
- If the EC is too low, add a small, proportional amount of each nutrient part.
Check our EC to PPM Converter if your feeding chart uses different units.
The Math Behind the Calculator
Educational grams estimate only: assumed 1.2 EC per g/L; fixed Grow/Micro/Bloom ratios 50/30/20 (veg), 20/30/50 (flower). No product calibration, liquid dosing, custom recipes or source-water EC. Follow your manufacturer’s recipe and measure EC. Total example grams = EC ÷ 1.2 × liters. The conversion is an assumption, not a measured property of your nutrient product.
Common Mistakes
- Ignoring source water EC. If your tap water starts at 0.4 mS/cm and you dose for a target of 1.8 mS/cm, you should only add enough nutrient to raise EC by 1.4, not 1.8 — otherwise you overshoot.
- Mixing concentrates directly together. Part A (calcium-heavy) and Part B (phosphate/sulfate-heavy) will precipitate into a chalky, unusable solid if combined before dilution — always add each part to water separately.
- Trusting PPM without knowing the conversion scale. PPM meters use either a 0.5 or 0.7 conversion factor from EC; a "700 ppm" reading means different things depending on which scale your meter uses. Always check your meter's spec sheet.
- Not accounting for evaporation vs. uptake. As plants transpire, water leaves faster than nutrients are consumed, so EC rises over the week even without topping off — top off with plain water, not more nutrient solution, unless your EC has actually dropped.
Worked Examples
For 40 L and EC 1.4, the example totals 46.7 g. Vegetative splits are Grow 23.3 g, Micro 14.0 g and Bloom 9.3 g. These illustrate arithmetic only; they are not a recipe for any named product.
See Also
- EC vs pH Guide — Mastering the two primary metrics.
- Cal-Mag Supplementation — When your base nutrients aren't enough.
- Hydroponic Nutrient Deficiency Guide — Spotting the signs of a bad mix.
- Hydroponic Parameter Reference — pH/EC/DLI targets across common crops.
FAQ
Should I mix nutrients directly in the reservoir?
No. Always add nutrients one by one to a partially filled reservoir and mix thoroughly between each. Never mix "A" and "B" concentrates together directly, or they will precipitate (turn into unusable solids).
What is the "Lucas Formula"?
A famous simplified 2-part recipe using General Hydroponics Flora Series (8ml Micro / 16ml Bloom per gallon) that works for most growth stages.
Do I need to change my reservoir every week?
For small systems, a full change every 7-14 days is recommended to prevent "nutrient imbalance" where plants eat all of one element but leave the others.