Pool Calcium Hardness Calculator Australia
Estimate the calcium chloride needed to raise calcium hardness, then adjust for the concentration printed on your product. Low hardness can damage some surfaces; excessive hardness encourages scale.
Use your actual pool readingsOpen the calculator for a dose based on pool type, volume, and current test result.Choose the target for your pool surface
- Concrete and plaster pools usually need more calcium than fibreglass or vinyl pools; use the surface manufacturer’s range.
- The site calculator uses a broad 200–400 ppm band for general pool diagnosis.
- Naked Pools currently recommends surface-specific ranges, including 150–250 ppm for concrete and 80–150 ppm for fibreglass/vinyl.
Australian dose chart
The chart estimates anhydrous calcium chloride. Commercial products vary in concentration and hydration, so divide by the active fraction or use the manufacturer’s label dose.
| Pool volume | Raise hardness by 25 ppm | Raise hardness by 50 ppm |
|---|---|---|
| 30,000 L | ~830 g | ~1.7 kg |
| 50,000 L | ~1.4 kg | ~2.8 kg |
| 75,000 L | ~2.1 kg | ~4.2 kg |
| 100,000 L | ~2.8 kg | ~5.6 kg |
How to dose without overshooting
- Test calcium hardness and confirm the target for your pool surface and equipment.
- Calculate only the increase required; hardness is much easier to add than remove.
- Adjust the estimate for the product concentration shown on its label.
- Split larger corrections into stages with the pump running and brush any settled product.
- Allow full circulation, then retest before adding the remainder.
Safety and system checks
- Adding calcium chloride to water releases heat. Follow the label and use eye, skin, and respiratory protection.
- Do not add calcium chloride at the same time as bicarbonate, carbonate, or chlorine products.
- High hardness is normally managed through water replacement and overall water balance, not another additive.