What this tool does
Builds a ordered correction plan for an existing reservoir: pH steps first when out of range, then EC up/down.
Scales doses to reservoir volume (litres or L×W×depth).
Includes separate A+B mix and NPK ratio helpers for fresh tanks.
How it works
- Stage targets from plant nutrients JSON, or FALLBACK_STAGE EC 0.8–1.6 mS/cm and pH 5.8–6.3.
- pH down/up dose: raw mL = volume_L × |ΔpH| × strength (default 0.15 mL/L per pH unit down, 0.2 up); UI starts at 50% of raw.
- EC raise toward midpoint: ml per part ≈ (volume_L × ecGap) / nutrientStrength / 2 for A and B; default nutrientStrength 0.4 mS/cm per (mL/L) of concentrate.
- EC high: dilution volume = (currentEC × volumeL) / ecMid − volumeL water to add.
- PH_TOLERANCE 0.05; PH_CRITICAL_DELTA 0.5 triggers stronger pH-first messaging.
Assumptions and default values
| Default nutrient strength | 0.4 mS/cm rise per (mL/L) of A+B concentrate |
|---|---|
| pH Down strength | 0.15 mL/L per pH unit |
| pH Up strength | 0.2 mL/L per pH unit |
| Fallback EC / pH band | 0.8–1.6 mS/cm, pH 5.8–6.3 |
Worked example
Computed with the same functions as the live tool.
Inputs
| Reservoir | 20 L |
|---|---|
| Current pH | 6.8 |
| Current EC | 1 mS/cm |
Outputs
| Suggested pH Down start | 0.97 mL (50% of raw estimate) |
|---|---|
| EC raise (A+B total, approx.) | 10 mL toward midpoint 1.2 mS/cm |
Limitations
- Does not replace a lab water analysis or stock-specific label instructions.
- Assumes generic concentrate strengths — adjust strengths in the UI if your product differs.
- Does not model temperature-dependent pH drift over hours.
FAQ
Why fix pH before adding nutrients?
The plan always inserts pH correction before EC dosing when pH is outside the band, because nutrient salts shift pH and EC readings taken in a broken pH range are misleading.
How accurate are EC and pH targets?
Targets come from per-stage fields on each plant when available; otherwise the fallback band above is used.
Does it support odd tank shapes?
Yes — enter litres directly or length × width × water depth to compute volume.
Why only half the calculated pH dose?
The code uses 50% of the calculated pH adjuster volume as the starting suggestion to reduce over-correction risk.
What if EC and pH are both fine?
The plan tells you to maintain and re-test in 24 h or after a top-up.