Alkalinity Up Calculator for Hydroponics
K2CO3 (carbonate) & KHCO3 (bicarbonate) Dose for Nutrient Solutions
Example Hydroponic Alkalinity Adjustment Calculation
This example shows how the water alkalinity adjustment calculator estimates the carbonate or bicarbonate required to raise the alkalinity of a hydroponic nutrient solution.
Example input data
- Material: Potassium carbonate (K2CO3)
- Reservoir volume: 100 L
- Current pH: 5.0
- Current alkalinity as CaCO3: 5 ppm
- Target alkalinity as CaCO3: 70 ppm
- Water: RO - Ca: 2 ppm; Mg: 2 ppm
Calculation result
Results show total KOH required and step-by-step dosing for precise pH adjustment.
Alkalinity Increase Requirement (Carbonate Buffer)
This summary shows how much Potassium carbonate (K2CO3) is required to raise water alkalinity to the target level in a 100 liter reservoir. The calculation includes the expected final pH and the amount of potassium (K) added to the nutrient solution.
| Parameter | Calculated value |
|---|---|
| Salt | Potassium carbonate (K2CO3) |
| Total salt required | 8.98 g |
| Potassium added (K) | 50.78 ppm |
| Final pH | 8.17 |
| Reservoir volume | 100 L |
• Carbonate buffers (such as potassium carbonate or potassium bicarbonate) increase both water alkalinity (ppm as CaCO₃) and pH.
• Potassium contribution should be accounted for in nutrient-balanced systems.
• Based on these results, the total carbonate dose can be safely divided into multiple steps to achieve the target alkalinity while keeping pH within a controllable range.
Step-by-step Alkalinity Adjustment Plan
The table below shows a step-by-step alkalinity dosing schedule, dividing the total carbonate buffer requirement into smaller additions. This gradual approach is recommended for hydroponics, coco, and RO water, as it helps prevent sudden pH spikes and improves overall solution stability in recirculating systems.
| Dose | Salt | Potassium(K) | Δ Alk | Δ pH |
|---|---|---|---|---|
| 1 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.92 |
| 2 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.68 |
| 3 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.38 |
| 4 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.23 |
| 5 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.20 |
| 6 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.18 |
| 7 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.17 |
| 8 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.16 |
| 9 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.14 |
| 10 | +897.6 mg | +507.8 mg | +6.5 ppm | +0.13 |
Column definitions:
- Dose – Sequential dosing step. Each step represents a controlled carbonate salt addition.
- Salt – Amount of carbonate buffer to add at this step, calculated for the full reservoir volume.
- Potassium (K) – Potassium contribution from the carbonate salt at this dose. This value should be considered in nutrient-balanced hydroponic systems.
- Δ Alk – Increase in water alkalinity (ppm as CaCO₃) achieved by this dose.
- Δ pH – Estimated pH increase after the solution reaches equilibrium following this dose.
• Mix thoroughly and allow the solution to stabilize before measuring pH after each dose.
• Smaller and more frequent doses are strongly recommended for RO or very low-alkalinity water.
This example illustrates estimated carbonate or bicarbonate doses based on solution volume, initial pH, initial alkalinity, and target alkalinity. Actual water response may vary, always verify pH after dosing.
Stabilize Your Water pH
Increase alkalinity and keep your nutrient solution stable
Related Materials
Calculators
EC Nutrient Balance Calculator for Hydroponics & Drift Correction for Nutrient Solutions
Balance nutrients and correct EC drift in hydroponic solutions.
pH Down Calculator for Hydroponics | Acid Dose for Nutrient Solutions
Calculate the correct acid dose to safely lower water and nutrient solution pH.
Blogs
EC, Nutrients, pH & Alkalinity: Complete Hydroponic Nutrient Solution Guide
A practical guide to preparing stable hydroponic nutrient solutions with EC, pH, alkalinity, and water analysis.
Using acids in Hydroponics, Irrigation & Fertigation
A complete guide to pH control, alkalinity reduction, nutrient balance — and which acids are best for each task.
Frequently Asked Questions
- Low-alkalinity water has very little buffering capacity, which causes rapid and unpredictable pH fluctuations. Increasing water alkalinity helps stabilize pH over time, protects plant roots, improves nutrient uptake, and prevents sudden pH drops in hydroponic, fertigation, and recirculating systems.
