Worked examples
| Product example | Price / stated basis | Calculation | Estimated salt cost |
|---|---|---|---|
| Red Sea Coral Pro 22 kg | £74.99 / 660 L stated | £74.99 ÷ 660 | About £0.114 per L |
| Aquaforest Reef Salt 25 kg | £74.90 / 390 g per 10 L at 33 ppt | 25,000 g ÷ 39 g/L ≈ 641 L; £74.90 ÷ 641 | About £0.117 per L |
| Red Sea Coral Pro 22 kg, 100 L change | Using the £0.114/L estimate | 100 × £0.114 | About £11.40 in salt |
Monthly planning example
If a system changes 80 litres each month, the salt-only estimate is roughly £9.12 using the Red Sea Coral Pro example. At 160 litres, it is roughly £18.24. That excludes RODI waste, electricity, delivery, replacement test reagents, containers, mixing pumps and any additives needed to maintain the tank between changes.
Why your actual cost can differ
- Your salinity target changes the grams needed per litre.
- Moisture and clumping can make a stored salt less consistent by weight.
- Shipping can dominate the cost of a single bucket.
- A salt with a higher starting alkalinity may change your dosing requirement after a water change.
- A retailer’s stated yield may use a different salinity basis from your target.
A simple spreadsheet formula
Cost per litre = pack price ÷ stated litres produced. Then use monthly salt spend = litres changed per month × cost per litre. Keep the pack size, checked date, stated salinity and retailer beside the number so a future price refresh does not silently change the conclusion.
Sources and limitations
Price and yield examples were checked against Red Sea Coral Pro and Aquaforest Reef Salt. The calculations are arithmetic illustrations, not a promise of exact consumption or shipping cost.