How Much Salt to Add to Your Saltwater Pool — Calculator
Calculate how many pounds of pool salt to add to reach your target salinity level for a saltwater chlorine generator.
Always measure before adding
Salt test strips are inaccurate — use a digital salinity meter or take a sample to a pool store. Adding too much salt requires a partial drain to correct. When in doubt, add half the calculated dose and retest after 24 hours.
How salt levels change in your pool
Salt is measured in parts per million (ppm). Most salt chlorine generators (SWGs) operate best in the range of 2700–3400 ppm — check your SWG manual for the exact target, since different brands have different requirements.
The dose is straightforward: salt doesn't evaporate or get used up chemically. Once it's in the water, it stays until you dilute the pool. You only need to add salt to compensate for water lost to splashing, backwashing, leaks, or fresh water added to refill.
Salt doesn't disappear — it dilutes
Unlike chlorine, salt isn't consumed by the SWG. The cell splits water into chlorine and hydrogen gas, but the sodium and chloride ions recombine and stay in solution. Salt level only drops when pool water is removed or diluted.
How the salt dose is calculated
The formula uses the fact that water weighs approximately 8.34 lbs per gallon:
Salt to add (lbs) = (target ppm − current ppm) × pool gallons × 0.00000834
This calculates the mass of dissolved salt needed to raise the concentration by the target amount. Because pool salt is essentially pure NaCl (≥ 99%), no purity correction is needed for standard pool salt products.
Worked example
A 15,000-gallon pool tests at 2,200 ppm. The SWG target is 3,200 ppm — a rise of 1,000 ppm.
Salt needed = 1,000 × 15,000 × 0.00000834 = 125 lbs ≈ 3 bags of 40 lb pool salt (with a small amount left over). Broadcast the salt evenly across the pool with the pump running, then brush undissolved crystals off the floor. Retest after 24 hours of circulation before adjusting further.
Do not add salt near the skimmer or SWG cell
Concentrated salt can damage the salt cell if poured directly into the skimmer. Broadcast it evenly across the shallow end of the pool with the pump running. Never add more than 10 lbs at a time in a small area — let it circulate and dissolve before the next addition.
What kind of salt to use
Use plain sodium chloride (NaCl) with at least 99% purity. Specifically:
- No iodine (iodized salt will stain pool surfaces)
- No anti-caking agents such as yellow prussiate of soda
- No additives or minerals
Pool salt, food-grade salt (non-iodized), and pure water softener salt all work. Many pool supply stores and wholesale clubs sell 40 lb bags labeled specifically for pools. Read the label — "pure NaCl" or "99.8% sodium chloride" is what you want.
Frequently asked questions
What salt level should I target for a saltwater pool?
Most SWGs perform best at 2700–3400 ppm. Always check your manufacturer's manual — Pentair, Hayward, Jandy, and other brands each publish their own recommended range and will display low-salt warnings when the level drops below their threshold. Running salt too high (above 4000–5000 ppm) can shorten cell life and corrode metal fittings.
How long does pool salt take to dissolve?
With the pump running, granular pool salt dissolves within 24 hours. Brush any crystals you can see off the pool floor — don't let them sit against plaster or vinyl. Do not run your SWG until the salt is fully dissolved and circulated; a meter read before full dissolution will show a lower level than the actual final level.
Will adding salt change my pH or alkalinity?
No. Sodium chloride is pH-neutral and has no effect on total alkalinity, pH, calcium hardness, or CYA. Adding salt requires no other chemistry adjustments on its own. That said, saltwater pools naturally tend toward rising pH over time due to the electrolysis process — track pH regularly and adjust with muriatic acid as needed.
Can I add too much salt to a pool?
Yes. Salt above 4000–5000 ppm can damage your SWG cell and accelerate corrosion of metal fittings, ladders, and heater components. If salt is too high, the only correction is dilution — partially drain the pool and refill with fresh water. There is no chemical that removes dissolved salt.
Why do I keep losing salt?
Salt level drops only when pool water leaves the pool: backwashing, splashing, overflow from rain, draining for winterization, or a leak. If your salt level keeps dropping without an obvious cause, check for a slow leak. The SWG itself does not consume salt — it converts chloride ions to chlorine and back in a cycle that leaves the salt level unchanged.
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