Nutrient mixing order is what keeps salts in solution instead of falling out as precipitate in the tank: the Mulder pair weights flag the collision pairs, Ca-P at 0.4, Ca-Mg at 0.6 and K-Mg at 0.7, so the sequence you dissolve in decides whether the elements stay available. A 100 L recipe worked from crop optimum ppm, lettuce 150-50-200 Ca-Mg-K, shows the order salt by salt and the ppm budget each addition is supposed to land.
Key takeaways
- Open the Pro row — Zinc, water temperature and pH fine-tune the solver: warm water raises every antagonism strength, and pH outside 5.5-6.5 slows each ion about 10%.
- Run the Mulder matrix — Every ion i gets the mean of its antagonist strengths (weight x rival ppm / 100).
- Optimal Ca-Mg-K per crop (ppm): lettuce 150-50-200, tomato 200-60-300, cucumber 160-55-230, basil 140-45-180, strawberry 170-55-210.
- Na, Fe, Mn, P, Zn reference targets are 0-3-1-40-0.5.
How Nutrient Antagonism Lockout Predictor Mulder Matrix Solver Helps You Master This
- Enter the feed profile — Type the calcium, magnesium and potassium ppm from your last lab or meter reading, pick the crop, and set the water EC.
- Add the secondary ions — Sodium, iron, manganese and phosphorus change the matrix. Sodium competes with calcium and magnesium, and the Fe-Mn pair is a classic lockout both ways.
- Open the Pro row — Zinc, water temperature and pH fine-tune the solver: warm water raises every antagonism strength, and pH outside 5.5-6.5 slows each ion about 10%.
- Run the Mulder matrix — Every ion i gets the mean of its antagonist strengths (weight x rival ppm / 100). That mean drives its uptake multiplier, and the per-ion antagonism score is the average across all eight ions times 10.
- Compare uptake to the crop optimum — Each ion uptake ratio is checked against the crop-optimal ratio. Lockout risk is how far that ion falls short, and the worst ion becomes the limiting ion.
- Read the correction dose — The correction dose is the gap between the crop-optimal concentration and modelled uptake, in ppm. Add the gap, re-run, and watch the gauge climb back above 80%.
The Formula Behind the Nutrient Mixing Order & Fallout Prevention
Mean antagonism toward ion i → A_i = frac{1}{k_i}sum_{j} w_{ij},frac{c_j}{100}Modelled ion uptake (ppm) → u_i = m_c, c_i,(1 - 0.5,A_i), f_{pH}, f_TUptake share of total → R_i = frac{u_i}{sum u},100Crop-optimal uptake ratio (%) → O_i = frac{c^{*}_i}{sum c^{*}},100Per-ion lockout risk (%) → L_i = mathrm{clamp}left(100 - frac{R_i}{O_i},100, 0, 100right)Total lockout risk (worst ion) → L = max_i L_iAntagonism score (/10) → S = mathrm{clamp}left(frac{1}{8}sum_i A_i cdot 10, 0, 10right)Correction dose (ppm to add) → D_i = maxleft(0, c^{*}_i - u_iright)
Target Ranges: What the Numbers Should Be
- Antagonist pair weights (0-1): Ca-Mg 0.6, Ca-K 0.5, Ca-Na 0.3, Ca-P 0.4, Mg-Ca 0.4, Mg-K 0.5, Mg-Na 0.5, K-Mg 0.7, K-Ca 0.6, K-Na 0.2, Na-Ca 0.8, Na-Mg 0.5, Fe-Mn 0.6, P-Zn 0.5. Higher means a stronger rival for uptake sites.
- Optimal Ca-Mg-K per crop (ppm): lettuce 150-50-200, tomato 200-60-300, cucumber 160-55-230, basil 140-45-180, strawberry 170-55-210. Na, Fe, Mn, P, Zn reference targets are 0-3-1-40-0.5.
- Uptake multiplier = 1 – 0.5 x mean antagonism, clamped to 0.1-1.0, scaled by crop multiplier, the pH factor (1.0 at 5.5-6.5, 0.9 outside) and temperature (1.0 at 20 C, 0.9 at 15 C, 1.1 at 30 C).
- Lockout risk compares the ion percent of total uptake against the crop-optimal percent: falling 10% short reads 10% risk; the worst ion sets total lockout risk and becomes the limiting ion.
- Correction dose = crop-optimal ppm minus modelled uptake ppm, floored at 0. Recheck the reservoir volume and salt table before dosing — this is per-ppm of the missing element, not the raw salt weight.
Use the free HOCl Solution Maker — Hypochlorous Acid & Bleach Dilution Blueprint to run the numbers on your own setup.
Use the free Climate Controller & HVAC Sizer — VPD, Dehumidifier & CO2 Blueprint to run the numbers on your own setup.
Use the free Nutrient Lab Pro — Elemental PPM Formulator to run the numbers on your own setup.
Compare every free calculator side-by-side on the MistCulture tools hub — each one keeps your workspace in sync.
Related guides
A 100 L lettuce recipe in mixing order
Targets for lettuce in 100 L: Ca 150, Mg 50, K 200 ppm, with reference targets of Na 0, Fe 3, Mn 1, P 40 and Zn 0.5 ppm. At 100 L, 1 ppm of any element is 0.1 g, so the recipe budget is fixed before a single bag opens.
- Element budget in 100 L: 15 g Ca, 5 g Mg, 20 g K, 4 g P, 0.3 g Fe, 0.1 g Mn, 0.05 g Zn.
- Order 1: dilute the 0.3 g Fe chelate with the 0.1 g Mn and 0.05 g Zn micros into the base water first, before any calcium or phosphate enters the tank.
- Order 2: dissolve the 4 g P and 5 g Mg sources into the dilute base; Order 3 adds the 20 g K, each fully dissolved before the next addition.
- Calcium last: the 15 g Ca as calcium nitrate goes in after everything else, because the Ca-P weight of 0.4 and the Ca-Mg weight of 0.6 are the two fallout risks in this formula.
- Verify the finished 100 L reads against the 150-50-200 optimum and keep pH inside 5.5-6.5, where the uptake factor sits at 1.0 and the recipe assumptions hold.
Frequently Asked Questions
References & Science
- Purdue Extension — hydroponics guide
- Cornell CALS — hydroponic research manual
- USDA National Agricultural Library
Frequently asked questions
What is the correct nutrient mixing order?
Micros first, iron and manganese and zinc diluted into the water before anything else, then magnesium, phosphate and potassium, and calcium as the last addition, each salt fully dissolved before the next. The Mulder pair weights are the map: Ca-P at 0.4 and Ca-Mg at 0.6 are the precipitation risks, so the calcium stock never meets the phosphate or magnesium concentrates directly.
What is the biggest mixing-order mistake?
Pouring a concentrated calcium stock into a base that already holds phosphate and magnesium. On the 100 L lettuce recipe that is a 15 g calcium packet meeting a 4 g P plus 5 g Mg base, and the Ca-P weight of 0.4 goes insoluble on contact. The ppm budget silently drops and the final EC reads low, so the tank looks mixed when it is not.
Which calculators help me batch a nutrient mix?
The Nutrient Antagonism Lockout Predictor on this page flags the element pairs that will fight in the tank before you mix, and Nutrient Lab Pro converts the per-crop ppm targets (lettuce 150-50-200 Ca-Mg-K) into salt weights for your reservoir volume so each step of the order lands the numbers it claims.
References
- Hoagland, D. R. & Arnon, D. I. (1950) — The Water-Culture Method for Growing Plants Without Soil
- Sonnenveld, C. & Voogt, W. — Plant Nutrition of Greenhouse Crops, Springer
- Resh, H. M. — Hydroponic Food Production (7th ed.), CRC Press
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