Pool salt dose calculator: from “low salt” to ready in one weekend
Salt math is simple, 50 g per 1,000 L raises salt by 1 ppm, but cell brand targets differ. Get the right number for your specific chlorinator and you’ll never over-salt the pool.
Last updated: 2 June 2026
Adding salt to a pool is straightforward chemistry: pure NaCl dissolved into water. The math is simple, 50 g of pool salt per 1,000 L raises salt by 1 ppm. The complication is that the right target depends on your salt chlorinator’s brand.
This page covers the dose math, the cell-brand-specific targets, and the application procedure to avoid the most common mistake: over-salting (which is a major drain-and-refill chore to fix).
Cell-brand salt targets
| Cell brand | Target salt (ppm) | Acceptable range |
|---|---|---|
| Hayward AquaRite | 3,200 | 2,700–3,400 |
| Pentair IntelliChlor IC40 | 3,400 | 3,200–3,800 |
| Astralpool VX9 / VX11 | 4,500 | 3,800–5,000 |
| Zodiac TRi / TRi-PRO | 3,800 | 3,500–4,000 |
| Zodiac eXO | 4,000 | 3,500–4,500 |
| Davey Cleartouch | 5,000 | 4,000–6,000 |
| K-Star MP25 | 4,000 | 3,500–4,500 |
Salt dose reference table
Dose in kg of pool-grade salt. Assumes starting salt of 0 ppm, for existing pools, subtract current salt level from target before calculating.
| Pool size (L) | 2,500 ppm | 3,200 ppm | 4,000 ppm | 5,000 ppm |
|---|---|---|---|---|
| 20,000 | 50 kg | 64 kg | 80 kg | 100 kg |
| 30,000 | 75 kg | 96 kg | 120 kg | 150 kg |
| 50,000 | 125 kg | 160 kg | 200 kg | 250 kg |
| 70,000 | 175 kg | 224 kg | 280 kg | 350 kg |
| 100,000 | 250 kg | 320 kg | 400 kg | 500 kg |
Adjustment math for existing pools
For an existing pool with current salt level X ppm and target Y ppm in a Z L pool:
Salt to add (kg) = (Y − X) × Z ÷ 20,000
Example
50,000 L pool with current salt 2,200 ppm, target 3,400 ppm (Pentair IntelliChlor):
Salt to add = (3,400 − 2,200) × 50,000 ÷ 20,000 = 1,200 × 2.5 = 3,000 g per 1,000 L × 50 = 60 kg of salt.
That’s 3 bags of 20 kg pool salt.
Salt grade, what to buy
| Salt type | Use for pools? | Notes |
|---|---|---|
| Pool salt (pure NaCl, dry granular) | YES | Industry standard. ~$0.50/kg in Australia. |
| Solar salt (less refined) | YES | Acceptable. Marginally cheaper. |
| Mined / rock salt | NO | Too impure, brown residue stains plaster. |
| Iodised table salt | NO | Iodine and anti-caking damage cells. |
| Sea salt | NO | Trace minerals stain pool surfaces. |
Application procedure
- Turn off the salt chlorinator. Important, don’t run the cell with undissolved salt.
- Brush across the deep end of the pool to clean any debris.
- Distribute salt evenly across the deep end. Don’t pour in one spot, concentrated salt can stain plaster locally.
- Run the pump on filter cycle for 24 hours.
- Brush any visible undissolved salt off the bottom mid-cycle to help dissolution.
- Re-test salt the next day before turning the chlorinator back on.
- Turn on chlorinator only after salt is verified at target.
If you over-salt
The only fix is dilution, drain a portion of pool water and refill with fresh. Math:
Replacing 25% of pool water drops salt by 25%. So going from 5,500 ppm to 4,000 ppm requires draining ~27% of the pool. Use the filter waste port or a submersible pump.
The under-dose principle: always dose at 70% of calculated. Re-test after 24 hours. Add the remaining 30% if needed. Over-salting is expensive to fix; under-salting is one more 20kg bag of salt away.
Sources & references
- Trouble Free Pool, ABCs of Pool Water Chemistry
- ANSI/APSP-11, Water Quality Standards in Public Pools
- AS 3633-1989, Private swimming pools (Australian Standard)
Frequently asked questions
How much salt do I add to my pool?
50 g of pool-grade salt per 1,000 L raises salt by 1 ppm. So a 50,000 L pool needs 60 kg of salt to raise from 2,200 to 3,400 ppm. Cell brand determines target: Hayward 3,200, Pentair 3,400, Astralpool 4,500, Zodiac 3,800.
Can I use table salt in my pool?
No. Iodised table salt contains iodine and anti-caking agents that damage salt cells. Use only pool-grade salt (pure NaCl), sold in 20kg bags at pool stores and hardware shops.
How long does salt take to dissolve in pool water?
Most salt dissolves within 12 hours with the pump running. Larger granules can take 24+ hours. Always brush any undissolved salt off the bottom mid-cycle to speed dissolution and prevent plaster damage.
What happens if I over-salt my pool?
The cell may go into ‘High Salt’ protection mode and stop producing chlorine. The only fix is dilution, drain and refill a portion of the pool to dilute. Replacing 25% of water drops salt by 25%.
Does the Water Test Calculator app calculate salt doses?
Yes. Enter your current salt level, cell brand (for the right target), and pool volume, the app calculates exact salt addition. Launching on iOS and Android in approximately 10 days.
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