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.
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.
Want the numbers worked out for you? Enter your pool volume and test results in our pool chemical calculator to see every dose in one check.
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.