Plant Care
- • Climate Control & VPD16
- • Disease & Pest Management14
- • Nutrient Solutions & EC34
- • Plant Health Monitoring7
Inputs
7 parameters · live recalculation on every change
PH
3.5pH
7pH default
8.5pH
PH
3.5pH
6pH default
8.5pH
L
5L
200L default
5000L
Advanced Settings — Deterministic Corrections
PPM CACO₃
0ppm CaCO₃
60ppm CaCO₃ default
500ppm CaCO₃
Deterministic model
7 inputs · 8 outputs
Runs 100% in your browser
This is a deterministic model: the same inputs always produce the same outputs, calculated entirely in your browser with nothing sent to any server. It is a planning aid — not a quote, not a dosing instruction, and not a yield forecast. Treat every line as a working estimate and validate it against your own prices and measurements.
It models one system: pH buffer architect. Runs the carbonate equilibrium and alkalinity titration for your reservoir — then doses the exact mL of acid or base, computes the carbonate / bicarbonate split, and maps the lockout zones so a 7.0-to-6.0 top-up never ends in a crash.
What the pH & Alkalinity Architect — Buffer Blueprint returns
The engine computes 8 outputs from your 7 inputs. The headline number is Acid Dose (mL), alongside Base Dose, Alkalinity After Shift, Carbonate (CO₃²⁻). Every output updates live as you change a parameter.
What it does not do
Outputs depend on the inputs and assumptions shown here. Confirm relevant measurements and local conditions before acting.
STEP 01
Enter current and target pH — the green band for most crops is 5.5–6.5, lettuce rides ~5.8, tomatoes ~6.0.
STEP 02
Set the reservoir volume; every dose in this tool scales linearly with it.
STEP 03
Know your water: enter the alkalinity in ppm CaCO₃ — RO sits ~0–20, tap 40–120, well water can exceed 150.
STEP 04
The engine runs carbonate speciation and buffer capacity from that alkalinity, so a high-alk feed demands visibly more acid.
STEP 05
Read the acid or base dose in mL, add in 1:10-diluted increments, distribute around the stilling zone.
STEP 06
Retest after 30 minutes and re-run — buffer chemistry keeps the real dose within a few percent of the first script.
\text{pH} = \text{pK}_{a} + \log\!\left( \frac{[\text{HCO}_3^-]}{[\text{H}_2\text{CO}_3]} \right)
Henderson-Hasselbalch — pH set by the bicarbonate/carbonic-acid ratio
\alpha_1 = \frac{10^{\text{pH}-6.35}}{1 + 10^{\text{pH}-6.35} + 10^{2\text{pH}-16.68}}
Carbonate speciation — the HCO₃⁻ fraction at a given pH
\text{Alk} = 50.04 \times ( [\text{HCO}_3^-] + 2[\text{CO}_3^{2-}] + [\text{OH}^-] - [\text{H}^+] )
Alkalinity titration — acid-consumed equivalents as CaCO₃
V_{acid} = V_{tank} \times \Delta\text{pH} \times k_{acid} \times \left( 1 + \tfrac{\text{Alk}}{400} \right)
Acid dose — buffering reserve scales the raw pH correction
V_{base} = V_{tank} \times \Delta\text{pH} \times k_{base} \times \left( 1 + \tfrac{\text{Alk}}{400} \right)
Base dose — mirrored for pH Up with its own strength constant
\beta = 0.1 + 0.3 \times \frac{\text{Alk}_{ppm}}{50.04}
Buffer capacity — mmol acid absorbed per litre per pH unit
pH is a ratio (Henderson-Hasselbalch), not a quantity — the dose to move 7.0→6.0 is NOT the same as 6.0→5.0, because the bicarbonate reservoir shrinks as pH drops.
High alkalinity is the quiet raid on your acid bottle: 200 ppm CaCO₃ water slurps phosphoric acid at roughly 1.5× the rate of a clean 40 ppm tap.
Below pH 4.5 phosphate and micronutrient metals precipitate visibly — the red band. Above 7.5 iron, manganese and zinc lock out. The map colours both.
The buffer-capacity figure is your drift forecast: balanced feeds near 0.35 mmol/L·pH walk gently; lean RO runs under that and swings within hours.
- Stumm, W., & Morgan, J.J. (2012). Aquatic Chemistry (3rd ed). Wiley — carbonate equilibrium constants pKa₁ = 6.35, pKa₂ = 10.33.
- Standard Methods for the Examination of Water & Wastewater — Alkalinity 2320 (CaCO₃ equivalent, 50.04 mg/meq).
This model combines the earlier Ph-adjuster, Alkalinity-calculator models.
Q1: What is alkalinity and why does it matter for pH? ▾
Alkalinity is the water’s buffering reserve — mostly bicarbonate in a healthy feed — measured in ppm CaCO₃. It is what fights the acid you add. Low-alkalinity RO water can swing from 7.0 to 5.5 on a few mL, while a 200 ppm well-water reserve swallows the same dose and barely moves. That is why two reservoirs can need wildly different amounts of pH Down to hit the same target.
Q2: What is pH lockout and how do I avoid it? ▾
Lockout is a window where plant-available nutrients become chemically unavailable. Below ~4.5 pH, phosphate and most micronutrients precipitate or get pushed out of plant-usable form; above ~7.5, iron, manganese and zinc lock. The Architect colours both ends red on the gauge and routes every target through a green 5.5–6.5 band so your recipe lands in the soluble window.
Q3: When should I use acid versus base? ▾
Acid (pH Down) lowers pH and is needed most of the time because nitrogen and phosphorus fertigation push pH upward. Base (pH Up) only earns its place when starting from a light, acidic source or after a heavy acid overshoot. The tool routes automatically: below target it returns the acid dose, above target the base dose — never both.
Q4: What does buffer capacity predict? ▾
Buffer capacity (mmol/L·pH) tells you how hard the feed resists pH drift. High-alkaline water lands near or above 0.6 and holds a set pH for days; lean RO feeds sit under 0.35 and drift within hours, especially as plant uptake shifts the balance. Using it you can forecast how often to retest and how much acid a full top-up will really cost.