Salt Pool Calculator
Calculate exactly how many pounds or bags of salt to add to your saltwater pool to reach the ideal 3,200 ppm.
Safety
Use only pure pool salt or food-grade NaCl — never rock salt or salt with anti-caking additives. Broadcast evenly around the pool with pump running. Salt dissolves in 24–48 hours. Do not add more than 200 lbs at once. Check your SWG manual for the recommended salt range.
To raise salinity, add about 83 lb (two 40-lb bags) per 10,000 gallons for every 1,000 ppm you need. Most cells want 2,700–3,400 ppm — follow your generator's manual, not a forum number. Use 99%+ pure pool salt, run the pump, and wait 24 hours before retesting. No chemical removes salt; only a partial drain lowers it. Enter your pool's numbers above for the exact amount.
A Salt Pool Is Still a Chlorine Pool
The most useful thing to understand about a saltwater pool is that it is not an alternative to chlorine — it is a way of making chlorine on site. The salt cell passes a current through the salty water and splits dissolved salt into chlorine, continuously, on the schedule you set. You are not choosing between salt and chlorine; you are growing your own instead of pouring it from a jug. Everything else — FC, pH, CYA, calcium — works exactly as it does in any chlorine pool.
Salinity itself sits around 3,200 ppm, with most systems happy anywhere in the 2,700–3,400 ppm range — low enough that the water tastes barely salty, far below the ocean's ~35,000 ppm.
The target is your cell's number, not the internet's
Every generator has its own preferred salinity, and it is printed in the manual. Run below it and the cell under-produces, throws a low-salt warning, and eventually stops making chlorine to protect itself. Run well above it and you invite corrosion on ladders, rails, and fittings, and some cells fault out at the top end. Find the range for your specific unit and aim for the middle of it — do not take a number off a forum for a different brand.
The good news is that salt is conservative: it does not evaporate and it is not used up making chlorine — the reaction recycles it. Salt only leaves the pool physically, through splash-out, backwashing, a winter drain-down, or rain overflowing the water line. So you set the level once at start-up, then top up a little a few times a season rather than chasing it constantly.
Raising it: pure pool salt
Use 99%+ pure sodium chloride — food-grade or pool-grade. Avoid rock salt, iodized table salt, and anything with anti-caking agents or yellow prussiate of soda; those additives stain and cloud the water. Broadcast it slowly across the pool with the pump running, brush any piles off the floor so they dissolve rather than sit, and run the pump about 24 hours before you trust a salinity reading. Test too early and you will read low and be tempted to overdose.
Salt Addition Chart
How much pool salt raises salinity by a given amount, at two common pool sizes.
| Salinity rise | Pool salt 10k gal |
Pool salt 20k gal |
|---|---|---|
| 500 ppm | 42 lb (1.0 bags) | 83 lb (2.1 bags) |
| 1,000 ppm | 83 lb (2.1 bags) | 167 lb (4.2 bags) |
| 1,500 ppm | 125 lb (3.1 bags) | 250 lb (6.3 bags) |
| 2,000 ppm | 167 lb (4.2 bags) | 333 lb (8.3 bags) |
| 3,000 ppm | 250 lb (6.3 bags) | 500 lb (12.5 bags) |
Bags are 40 lb. Add no more than about 200 lb at once and wait 24 hours between additions. A full fill from zero to ~3,200 ppm is a big first dose — enter your own numbers above for it.
Lowering it: dilution only
Because salt is conservative, nothing you add takes it back out — the only way down is to remove salty water and replace it with fresh. Usually you do not have to: rain and splash-out drift salinity slowly downward on their own. When you have genuinely overshot, a partial drain and refill is the fix, and the fraction to replace is the gap over the current level.
| Current salt | Target | Water to replace |
|---|---|---|
| 3,600 ppm | 3,200 ppm | 11% |
| 4,000 ppm | 3,200 ppm | 20% |
| 4,500 ppm | 3,200 ppm | 29% |
| 5,000 ppm | 3,200 ppm | 36% |
Assumes salt-free fill water. If you are only slightly high, waiting out a few rains is easier than draining.
The cell is what actually needs looking after
Salt pools rarely fail on salt — they fail on the cell. Calcium scales onto the plates over time, and a scaled cell produces less chlorine until it stops. Inspect it every few months; if you see white crust, soak it in a 4:1 water-to-muriatic-acid solution just until the fizzing stops. Only acid-wash when it is visibly scaled — every wash removes a little of the coating that makes the cell work, so over-cleaning is one of the surest ways to shorten its life. Expect a cell to last 3–7 years and to cost a few hundred dollars to replace; treating it well is the difference between the two ends of that range. The full method is in how to clean a salt cell.
One knock-on effect worth knowing: the cell drives pH upward as it runs, so salt pools need acid more regularly than they expect, and a low, stable alkalinity makes that easier to hold. Salt pools also run a higher stabilizer target — 60–80 ppm CYA — because the cell's steady low output benefits from more UV protection than a jug-fed pool. Set that with the CYA calculator, keep the rest of the panel in order with the water balance calculator, and see the saltwater pool guide for the full routine.