Measure your reservoir in litres and choose the target electrical conductivity for the current growth stage. Veg runs 1.2–2.0 mS/cm, flower 1.8–2.6 mS/cm, clones stay lower for safety.

Input your tap or RO water PPM on the 500 scale. The engine subtracts this baseline from total dissolved solids so fertiliser is not double-counted.

Select Masterblend 4-18-38, two-part A/B, one-part crystal, or DIY dry salts. Each profile uses its guaranteed analysis ratios to split nutrients.

Total feed equals EC times 700. Subtract source PPM to obtain the true fertiliser portion available for elemental distribution across the tank.

Multiply the fertiliser portion by each element coefficient for N, P, K, Ca, Mg and S. Scaling stays linear with EC for predictable transitions.

Add silica for extra potassium or CalMag for calcium and magnesium, then read cost per litre and batch cost. Verify EC against the lockout ceiling.