How much salt for a 18,000 gallon pool?
A fresh 18,000 gallon pool needs 480 lb of salt to reach 3,200 ppm, which is 12 bags of 40 lb pool salt. If you already have some salt in the water, use the table to find your starting point.
Rule of thumb: 1 lb of salt per 1,000 gallons raises salinity 120 ppm. For 18,000 gallons, every 40 lb bag adds about 267 ppm.
Salt doses for 18,000 gallons
| Current salt | Salt to add to reach 3,200 ppm | 40 lb bags |
|---|---|---|
| 0 ppm | 480 lb | 12 |
| 1,000 ppm | 330 lb | 9 |
| 2,000 ppm | 180 lb | 5 |
| 2,500 ppm | 105 lb | 3 |
| 3,000 ppm | 30 lb | 1 |
Check your cell's target first
Most chlorinators want 2,700 to 3,400 ppm, but some want 4,000 or more. The manual or the display on the control box tells you. Overshooting is annoying because salt only leaves by dilution.
Which salt
99% pure sodium chloride sold as pool salt, or plain water softener salt with no rust inhibitor or iodine. Don't use rock salt with anti-caking agents.
Adding it
Cell off, pump on. Pour bags into the shallow end and brush the piles until they dissolve. Wait 24 hours, then retest and turn the cell back on.
Other pool sizes
Salt for a 5,000, 8,000, 10,000, 12,000, 15,000, 20,000, 25,000, 30,000 gallon pool. Not a round number? Use the salt calculator with your exact volume, or find it with the volume calculator.
Other chemicals for 18,000 gallons
How much shock for a 18,000 gallon pool, How much chlorine for a 18,000 gallon pool, How much baking soda for a 18,000 gallon pool.