🧠 Core Concepts

Understand the science and theory before diving into the application.

What is Electrical Conductivity (EC)?

EC measures the total dissolved nutrients (salts) in your solution. It's measured in millisiemens per centimeter (mS/cm).

• Low EC (0.8–1.2): Few nutrients; good for seedlings to avoid burn
• Medium EC (1.2–2.0): Moderate nutrition; suitable for most growth stages
• High EC (2.0–2.8+): Dense nutrition; for blooming/fruiting or high-demand crops

Rule of thumb: Start low, increase gradually. It's easier to add than remove nutrients.

The NPK Macro-Triad

N-P-K are the three primary macronutrients your plants need most:

• Nitrogen (N): Drives leaf and stem growth; essential for vegetative stages
• Phosphorus (P): Critical for root development and flower/fruit formation
• Potassium (K): Strengthens plants, improves stress tolerance, enhances fruit quality

N-P-K ratios shift based on crop and growth stage. Vegetative stages want high N; flowering wants low N, high P-K.

Why A/B Split Solutions?

One core chemistry principle: calcium and sulfate cannot coexist in high concentrations without precipitating.

To avoid this:

• Part A (Calcium): Contains calcium nitrate + other cations (K, Mg) + micronutrients
• Part B (Sulfate/Phosphate): Contains potassium sulfate, phosphate, additional magnesium sulfate

They're mixed separately in water, then combined only at final dilution (1:100 ratio).

Macronutrients vs. Micronutrients

Macronutrients (needed in large quantities):

• Primary: N, P, K (often 50–300 ppm each)
• Secondary: Ca, Mg, S (often 40–150 ppm each)

Micronutrients (needed in tiny quantities):

• B, Fe, Mn, Zn, Cu, Mo, Ni (typically 0.05–2.0 ppm each)
• Imbalance is rare unless you use well water with unusual mineral content

pH and Nutrient Availability

Plant roots absorb nutrients best at specific pH ranges. Most hydroponic crops prefer pH 5.5–6.5:

• Too acidic (pH < 5.0): Iron, manganese, copper become toxic; calcium, magnesium become deficient
• Too basic (pH > 7.0): Iron, manganese, zinc become deficient; lockout occurs

Best practice: Measure pH; adjust with phosphoric acid (lower) or potassium hydroxide (raise).

Stock Concentration Ratios

NutriCalc assumes a 100× concentrate — meaning you mix concentrated solutions, then dilute 1:100 for the final reservoir:

• 30 mL concentrate + 2,970 mL water = 3 L of final solution

Why concentrates?

• Easier to store (takes up less space)
• Longer shelf life (concentrated solutions resist degradation)
• Reproducible (scales proportionally)

You can adjust strength:

• 50× concentrate: Larger volumes, easier to measure, less precise
• 100× concentrate: Balance of convenience and precision (recommended)
• 200× concentrate: Tiny volumes, requires precise scales, higher precision

Compatibility & Precipitation Risks

NutriCalc warns about five major compatibility issues:

Risk	Cause	Solution
Ca²⁺ + SO₄²⁻ precipitation	CaSO₄ crystals form	Use A/B split (automatic)
Ca²⁺ + PO₄³⁻ precipitation	Ca₃(PO₄)₂ crystals	Reduce Ca or P slightly
Iron solubility loss	Fe oxidizes at high pH	Lower pH to 5.5; use chelated Fe
NH₄⁺ toxicity	High ammonium > 10% of N	Use nitrate-based nitrogen sources
Boric acid solubility	Boric acid precipitates > 4.7 g/L	Limit boron to 2.0 ppm or less

The NutriCalc Solver (How It Works)

Behind the scenes, NutriCalc uses Singular Value Decomposition (SVD) — a mathematical technique that:

1. Takes your target nutrient levels (ppm)
2. Looks at available chemicals in your library
3. Solves a system of equations to find the exact quantities of each chemical
4. Reports element deviations so you know accuracy

Why SVD? Because there's usually no exact solution — chemicals have multiple nutrients. SVD finds the best approximation.

Cost Optimization

NutriCalc tracks chemical costs to help you find the cheapest formulation that still meets your targets.

• Different chemicals have different costs
• Cheaper sources may exist; prices vary by region and supplier
• Update prices regularly in the Chemical Library for accurate cost tracking