How much salt for an 18 ft pool
Starting from fresh water, an 18 ft Intex pool needs 120 to 175 pounds of salt. Depending on wall height and frame style, that's 3 to 5 bags. Those amounts come from Intex's salt table, set for 3,000 ppm (parts per million, the number a salt test shows).
What's the right salt amount for your 18 ft pool?
Look for your size down the page. With an Easy Set, the 18x42 model holds 4,786 gallons and calls for 120 pounds. The 18x48 version holds 5,455 gallons and calls for 135 pounds. The 18x52 version holds 5,894 gallons and calls for 150 pounds.
Intex figures frame pools at 90% full, while Easy Set pools are figured at 80%. The 18x48 frame model holds 6,423 gallons and needs 160 pounds. The 18x52 frame model holds 6,981 gallons and needs 175 pounds. Your salt level should stay between 2,500 and 3,500 ppm. Once it's poured in, let the pump run 24 hours nonstop so it dissolves, as the Intex manual says.
| Intex pool | Gallons | Startup salt | Code 91 top-up |
|---|---|---|---|
| Easy Set 18 ft x 42 in | 4,786 | Buy 3 bags · add 120 lb | 30 lb |
| Easy Set 18 ft x 48 in | 5,455 | Buy 4 bags · add 135 lb | 35 lb |
| Easy Set 18 ft x 52 in | 5,894 | Buy 4 bags · add 150 lb | 40 lb |
| Metal Frame 18 ft x 48 in | 6,423 | Buy 4 bags · add 160 lb | 40 lb |
| Metal Frame 18 ft x 52 in | 6,981 | Buy 5 bags · add 175 lb | 45 lb |
| Ultra Frame 18 ft x 52 in | 6,981 | Buy 5 bags · add 175 lb | 45 lb |
| Sequoia Spirit 18 ft 8 inx53 in | 6,981 | Buy 5 bags · add 175 lb | 45 lb |
Every row doses to 3,000 ppm. Pounds and gallons come straight off the Intex salt table, and the gallons are the water Intex says the pool holds when filled.
Easy Set or frame: which one do I have?
When Intex figures gallons, Easy Set pools get filled to 80% while frame pools go to 90%.
A frame pool needs extra salt for that reason.
Own an 18 ft pool that isn't an Intex?
Intex's own figures are the 80% and 90% fill levels. With any other pool, turn to the round-pool formula found in Hayward's manual. Take diameter times diameter times average depth times 5.9.
Imagine the water sits 4 ft deep. Work out 18 times 18 times 4 times 5.9. That comes to roughly 7,646 gallons.
Next, look in your chlorinator's manual to find the salt level it wants. Intex shoots for 3,000 ppm. Intex holds cyanuric acid at about 1% of the salt level.
Questions people bring to the counter
Is it possible to put in too much salt?
Yes. The top of Intex's range is 3,500 ppm, and seeing code E92 tells you salt has gone too high. Take out roughly 25% of the water and top back up with fresh. Repeat until code 92 disappears. That comes straight from Intex's error code guide. These codes can also trip when the water hits 35 °C or higher. See if bringing the temperature down helps.
How can I tell whether my saltwater pool has enough salt?
A test should read between 2,500 and 3,500 ppm. Try to land at 3,000 ppm. An Intex unit flashes code E91 when salt falls too low. Added the manual's salt dose and code 91 is still showing? Don't put in more salt.
What's the gallon count for an 18 ft pool with 48 in of depth?
At 80% capacity, an Intex 18x48 Easy Set pool takes 5,455 gallons. At 90% capacity, an Intex 18x48 frame pool takes 6,423 gallons.
What's the gallon count on an 18 ft round pool?
Depth matters, plus whether the pool is an Easy Set or a frame. Each size appears with its gallons in Intex's salt table. Got a round pool from another brand? Take 18 times 18 times the average depth times 5.9.