Inputs
Example data table
| Scenario | Volume | Current Alk | Target Alk | Acid | Strength | Estimated Dose |
|---|---|---|---|---|---|---|
| Small mixing tank | 100 L | 180 ppm | 100 ppm | Sodium bisulfate | 93% | ~41.3 g |
| Fertigation tote | 275 gal | 220 ppm | 120 ppm | Sodium bisulfate | 93% | ~826 g |
| Custom acid demo | 1.0 m³ | 150 ppm | 80 ppm | Custom (100 g/mol, 1 H+) | 100% | ~140 g |
Formula used
Alkalinity is commonly reported as ppm (mg/L) as CaCO3. To reduce alkalinity, you neutralize carbonate alkalinity with acid equivalents (H+).
- ΔAlk = Current − Target (ppm as CaCO3)
- Total mg CaCO3 = ΔAlk × Volume(L)
- meq = (Total mg CaCO3) ÷ 50
- moles H+ = meq ÷ 1000
- grams pure acid = (moles H+ ÷ n) × molar mass
- grams product = grams pure ÷ (strength/100) × (1 + safety/100)
Note: Real systems can deviate due to buffering, incomplete mixing, injection point losses, and lab variation.
How to use this calculator
- Measure alkalinity from a reliable water test report.
- Pick a target alkalinity suited to your crop and media.
- Select your dry acid product and enter its strength.
- Start with split additions and mix thoroughly each step.
- Re-test alkalinity and pH, then fine tune cautiously.
Practical goal for alkalinity control
Alkalinity drives how strongly water resists pH change. In fertigation, high alkalinity can push media pH upward, reduce micronutrient availability, and stress injectors. A common operational target is to reduce alkalinity into a crop-friendly band, then let pH fall where the nutrient recipe expects. This calculator converts a measured alkalinity drop into an acid equivalent so you can set doses using clear numbers.
What the alkalinity numbers mean
Most labs report alkalinity as ppm (mg/L) as CaCO3. That format is convenient because 50 mg/L as CaCO3 equals 1 milliequivalent per liter (1 meq/L). When you lower alkalinity, you neutralize carbonate and bicarbonate species by supplying hydrogen ions. The tool uses ΔAlk, volume, and the 50 mg/meq conversion to compute total milliequivalents and the required moles of H+.
How dry acids translate to dose
Dry acids differ in molar mass and how many effective H+ they deliver per mole. Sodium bisulfate is treated as a one‑proton acid source, while citric acid can contribute three protons when fully dissociated. The calculator multiplies required moles of H+ by molar mass and divides by acidity (nH). It then adjusts for product strength and an optional safety factor, producing grams and pounds.
Why split additions improve outcomes
Single large additions can overshoot when mixing is imperfect or alkalinity tests vary. Split dosing reduces risk by creating checkpoints. Add one portion, circulate thoroughly, and re-measure alkalinity and pH before adding the next. Many operators start with 2–5 splits for new water sources, then tighten the process once results stabilize. Use the stock-solution option to plan a measured injection mix.
Quality controls and field notes
Keep units consistent, verify the lab’s alkalinity basis, and log temperature, source changes, and injector settings. Dose into a high‑turbulence zone, protect pumps from undissolved solids, and avoid adding near sensitive roots. Record alkalinity achieved and compare to the planned ΔAlk so you can refine safety factor, mixing time, and split count for your site. each season.
FAQs
Should I use pH instead of alkalinity for dosing?
Use alkalinity for dose planning because it measures buffering. pH can change quickly with aeration and salts. After dosing, confirm both alkalinity and pH so the nutrient recipe and media stay in the desired range.
What alkalinity units does the calculator expect?
Enter alkalinity as ppm (mg/L) reported “as CaCO3.” If your report uses meq/L, multiply by 50 to convert to ppm as CaCO3, then enter the converted values.
How accurate is the result in real irrigation systems?
Accuracy depends on mixing, injector placement, water chemistry, and testing error. Start with split additions, measure after each step, and adjust the safety factor until your achieved alkalinity matches the target consistently.
Can I make a stock solution from the dry acid?
Yes. Enter the intended stock volume in liters to see grams per liter. Dissolve slowly with strong agitation, keep the container vented, and prevent undissolved solids from entering pumps or emitters.
Why does acid type change the dose?
Different acids have different molar mass and effective acidity. The calculator uses those values to convert required hydrogen ions into grams of product. Product strength then adjusts the final amount you weigh out.
What safety precautions should I follow?
Wear gloves and eye protection, avoid inhaling dust, and add acid to water while mixing. Keep acids away from bleach and oxidizers. Label containers, store dry, and rinse tools after handling.