How to get the two numbers you need
The first is the pool's volume in gallons. A wrong volume makes every later figure wrong, so work it out from your pool's shape with the pool volume calculator if you do not already know it. The second is the salt level now, from a fresh test.
Then read the target from your own manual. Hayward's AquaRite manual calls 3,200 ppm optimal, while Pentair's Plus and LT guide says 3,600 ppm. On 20,000 gallons, that gap alone is about 67 pounds. Pentair's IC guide even shows two different ideal figures between its English and Spanish sections, so read the page for your exact model.
Hayward says to use only sodium chloride that is more than 99 percent pure. It says not to use rock salt, salt with yellow prussiate of soda, salt with anti-caking additives or iodized salt. On new plaster, it says to wait 10 to 14 days before adding any.
A worked example
Here is a 20,000 gallon pool reading 2,000 ppm, with a Hayward system and 40 pound bags. These lines come from the same formula the calculator above runs.
20,000 gallons, 2,000 ppm, Hayward
- 3200 − 2000 = 1200 ppm to add
- 20000 × 8.34 × 1200 ÷ 1000000 = 200.16 lb
- 6 bags of 40 lb, as 5 bags is just short
With a Pentair Plus or LT, the same pool takes about 267 pounds. If the reading is above the target, salt cannot be taken out, and Hayward says the only way is to partially drain and refill. A pool at 4,000 ppm with a 3,200 target needs about 20 percent of its water replaced, which on this pool is 4000 gallons. Salt is one part of the bill, and the pool maintenance calculator covers the rest.
Pounds of salt to reach 3,200 ppm
This is the target in Hayward's manual. Its printed chart gives 533 pounds for 20,000 gallons from zero, where this formula gives 534, as the chart tracks a slightly lighter gallon.
| Pool | From 0 ppm | From 1000 ppm | From 2000 ppm | From 2400 ppm |
|---|---|---|---|---|
| 10000 gal | 267 lb | 183 lb | 100 lb | 67 lb |
| 15000 gal | 400 lb | 275 lb | 150 lb | 100 lb |
| 20000 gal | 534 lb | 367 lb | 200 lb | 133 lb |
| 25000 gal | 667 lb | 459 lb | 250 lb | 167 lb |
| 30000 gal | 801 lb | 550 lb | 300 lb | 200 lb |
Mistakes with pool salt
- Using another maker's target. A 400 ppm gap between two makers is not a rounding error.
- Adding it all at once. Hayward says a display can take 24 hours to settle, and over-salting can only be undone by draining.
- The wrong kind of salt. Rock salt and salt with additives are on Hayward's list of what to avoid.
- Blaming evaporation. Hayward says salt is not lost to evaporation, so topping up with fresh water does not call for more.
- A guessed volume. The dose is only as good as the gallons you enter.
Questions
How much salt do I add to raise ppm?
Multiply gallons by 8.34, then by the rise in ppm, then divide by a million. Taking 20,000 gallons from 2,000 to 3,200 ppm comes to about 200 pounds. Hayward's own chart gives the same figure within a pound or so.
What salt level should my pool be?
The level your chlorinator's maker gives, as they differ. Hayward says 3,200 ppm is optimal, within 2,700 to 3,400. Pentair's Plus and LT guide says 3,600 ppm, within 2,600 to 4,500. Check the manual for your own model.
How many bags of salt for pool startup?
About 14 bags of 40 pounds for 20,000 gallons starting from no salt with a 3,200 ppm target. That is about 534 pounds. Test first, since Hayward warns there may already be salt in the pool, and wait 10 to 14 days on new plaster.
How much salt do I add to a 15,000-gallon pool?
About 400 pounds from no salt to 3,200 ppm, or about 450 pounds to 3,600 ppm. Most pools hold some salt already, so a test will usually bring this down. Add it in stages and test again before the last of it.
What happens if the salt level is too high?
You partially drain the pool and refill it, as Hayward says that is the only way to lower it. Hayward says salt can begin to be tasted at about 3,500 to 4,000 ppm, and Pentair warns of faster corrosion above 6,000 ppm.
What happens if the salt level is too low?
The chlorinator warns you, and it may not make chlorine as it should. Hayward's manual flashes a warning below 2,700 ppm and lists below 2,400 ppm as too low. Pentair's Plus and LT guide shows a low indication below 3,000 ppm.
When do I need a professional?
When the display and a test kit still disagree a day after adding salt, or a warning stays on at the right level. A pool service can test the water and check the cell. Do the same before draining a large share of a plaster or vinyl pool.
This pool salt figure is a plan, not a dose to pour in one go. Follow your chlorinator's manual and the label on the bag, and confirm with a fresh water test, since there may already be salt in the pool and a display can take a day to settle. Too much salt can only be fixed by draining and refilling, so add it in stages.
Sources and review
- AquaRite owner's manual, 092538 Rev D, Hayward, 2019.
- How much salt does the system require?, Hayward, no date shown, read November 2026.
- IntelliChlor Plus and LT installation and user's guide, Pentair, 2025.
- IntelliChlor installation and user's guide, Pentair, no date shown, read November 2026.
- Estimated use of water in the United States, conversion factors, U.S. Geological Survey, 2004.
- Pool operator handbook, appendix B, Pool & Hot Tub Alliance, 2021.
Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.
How this is calculated
Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.
The arithmetic
Salt
Pounds = Gallons × 8.34 × Rise in ppm ÷ 1,000,000
- Rise in ppm
- The target less your test reading
Worked through: 20000 × 8.34 × 1200 ÷ 1000000 = 200.16 lb
Replacing water
Share to replace = Excess ppm ÷ Level now
- Excess ppm
- Your test reading less the target
Worked through: 800 ÷ 4000 = 0.2
The constants, and where they come from
HAYWARD_SALT_PPM
Published figureHayward's best salt level and its range, in ppm
- target
- 3200
- low
- 2700
- high
- 3400
Applies to: Hayward AquaRite systems
Source: AquaRite owner's manual, Hayward, published 2019-10, read 2026-11. This source is about 7 years old, and it is the one the figure rests on.
Also from: How much salt does the system require?, Hayward, no date on the page, read 2026-11.
The manual calls 3,200 ppm optimal within 2,700 to 3,400. Its printed chart matches this calculator to within a pound or so.
PENTAIR_PLUS_SALT_PPM
Published figurePentair's salt target and range for Plus and LT, in ppm
- target
- 3600
- low
- 2600
- high
- 4500
Applies to: Pentair IntelliChlor Plus and LT systems
Source: IntelliChlor Plus and LT installation and user's guide, Pentair, published 2025, read 2026-11.
The guide's table gives 3,600 ppm in a range of 2,600 to 4,500, shows a low warning below 3,000 and warns of corrosion above 6,000.
PENTAIR_IC_SALT_PPM
Published range, narrowedPentair's salt target and range for IC models, in ppm
- target
- 3600
- low
- 3600
- high
- 4500
Applies to: Pentair IC15, IC20, IC40 and IC60 systems
Source: IntelliChlor installation and user's guide, Pentair, no date on the page, read 2026-11.
The English text gives 3,600 to 4,500, ideal 3,600. The Spanish section of the same file gives 3,000 to 4,500, ideal 3,400, so read your own manual.
POUNDS_PER_GALLON
Published figureWeight of a gallon of water, in pounds
Applies to: Fresh water
Source: Estimated use of water in the United States, conversion factors, U.S. Geological Survey, published 2004, read 2026-11. This source is about 22 years old, and it is the one the figure rests on.
Also from: Pool operator handbook, Appendix B, Pool and Hot Tub Alliance, published 2021, read 2026-11.
PHTA's handbook prints 8.33. Hayward's chart tracks about 8.33 and Pentair's about 8.35, and the difference is under a pound in most pools.
PARTS_PER_MILLION
DefinitionalWhat ppm is measured against
Applies to: Definitional, everywhere
True by definition, so there is nothing to cite. The derivation is below.
One part per million is one pound of salt in a million pounds of water, which is why the sum divides by a million.
What the labels mean
- Published figure:
- taken directly from the source named beside it.
- Published range, narrowed:
- a source publishes a range and this calculator uses a representative value from it.
- Definitional:
- true by definition, like the number of inches in a foot, so there is nothing to cite.
If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.
How to use the pool salt calculator
- 1
Find your pool's volume
- 2
Test the water for salt
- 3
Choose your chlorinator
- 4
Add the salt in stages, keeping some back
- 5
Wait, then test again before adding the rest
What this calculator assumes
Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.
- A gallon of water weighs 8.34 pounds
- The target comes from the manual of the system you choose
- Salt stays in the water, and evaporation does not remove it
- Bags are rounded up to whole bags
Pro tips
- Keep a bag back, and test again before the last of it
- Give the display a day to settle
- Buy salt above 99 percent pure, as Hayward says