Pool Chemical Dosing Calculator (Alkalinity, Calcium Hardness, Stabiliser)
How much sodium bicarbonate, calcium chloride or cyanuric acid to add to raise a pool's alkalinity, calcium hardness or stabiliser from today's reading to the one you want.
Results
The dashed line marks the value you entered.
What this tool does
A reading in mg/L is a mass per cubic metre, so the dose is the difference times the volume times a chemical factor: raising alkalinity by 1 mg/L as CaCO₃ takes 1.68 g of bicarbonate per cubic metre, raising calcium hardness by 1 mg/L takes 1.11 g of pure calcium chloride, and cyanuric acid goes in 1 g per mg/L. Flake calcium chloride is often only about 77 % pure, so enter the strength printed on the bag. Add in two or three portions, retest after circulating, and never mix chemicals in a bucket.
Formula
grams = (target − current) × volume (m³) × f ÷ strength · f = 84.007 ÷ 50.043 = 1.679 (bicarbonate, per mg/L alkalinity) · 110.98 ÷ 100.087 = 1.109 (CaCl₂) · 1 (cyanuric acid)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
vm | Water volume | m³ |
pc | What you want to raise | — |
cu | Current reading | mg/L |
tg | Target reading | mg/L |
pu | Strength of the product | % |
G | Amount of product to add | g |
K | The same in kilograms | kg |
PM | Product per cubic metre of water | g/m³ |
Worked example
- Water volume50 m³
- What you want to raise1
- Current reading80 mg/L
- Target reading100 mg/L
- Strength of the product100 %
- Amount of product to add1679 g
- The same in kilograms1.68 kg
- Product per cubic metre of water33.6 g/m³
Limitations
- Coverage and consumption figures vary between products. Take the values from the manufacturer's datasheet for the product you are actually using.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.