How the calculation works

Salt readings are in parts per million (ppm): 3,200 ppm means 3,200 parts of salt in a million parts of water, by weight. To raise the level, you add the difference as a share of the weight of the water in your pool.

Salt to add = pool volume × (target − current reading) ÷ 1,000,000 × weight of the water per gallon (or litre).
Weight of the water: the calculator takes water as 1 kg per litre, which is 8.345 lb per US gallon. The manuals use the same convention, treating 1 ppm as 1 milligram per litre (Hayward: 3.20 g/L = 3,200 ppm; Jandy: g/L × 1,000 = ppm), so the results line up with their salt charts.
Bags: the salt needed ÷ the bag weight, rounded up to whole bags.
One bag raises the level by bag weight ÷ (pool volume × weight per gallon ÷ 1,000,000).

Worked example

A 15,000 gallon pool reads 2,400 ppm and the chlorinator wants 3,200 ppm, a rise of 800 ppm. The salt needed is 15,000 × 800 ÷ 1,000,000 × 8.345 = 100.1 lb. That is 3 bags of 40 lb, with 19.9 lb left over. Each 40 lb bag raises this pool by about 320 ppm. If you add it in two stages, the first half is 50.1 lb.

In metric, a 50,000 litre pool going from 2,400 to 3,200 ppm needs 50,000 × 800 ÷ 1,000,000 = 40 kg: exactly 2 bags of 20 kg. Each 20 kg bag raises this pool by 400 ppm.

Which salt level to aim for

Every salt chlorinator is designed for its own range, and the manufacturers don't agree, so the level printed in your own manual (or on the unit) is the one to use. These are the figures in the manuals we checked:

Chlorinator	Recommended	Too low / too high
Hayward AquaRite	2,700–3,400 ppm, 3,200 optimal	"Check salt" light flashes below 2,700 ppm. High salt can shut it down; salt starts to taste at about 3,500–4,000 ppm.
Pentair IntelliChlor (2023 guide)	3,600–4,500 ppm, ideal 3,600	"Good salt" light from 2,800 to 4,500 ppm; it stops making chlorine below 2,600 ppm. Above 4,500 ppm raises the risk of corrosion.
Jandy AquaPure (APURE700, APURE1400)	3,000–3,500 ppm (3.0–3.5 g/L)	Below 2,000 ppm causes premature cell failure. Above 4,000 ppm may damage the control center; above 6,000 ppm may corrode pool fixtures.

An earlier Pentair IntelliChlor guide gave 3,000–4,500 ppm with 3,400 ppm as ideal, so check the guide that came with your unit. The calculator starts at 3,200 ppm because it is Hayward's optimum and sits inside Jandy's range, but pick your own chlorinator from the list or type its figure. Public pools covered by the CDC's Model Aquatic Health Code must keep salt in the range the manufacturer specifies.

Salt tests vary. Pentair says readings differ between test strips, electronic testers and titration, and that its own sensor is accurate to within 500 ppm, so check the cell's reading with a separate reliable test before you add a lot of salt. Hayward suggests having the level checked professionally before adding large amounts.

Adding salt

Which salt to buy

Pure sodium chloride. Hayward asks for salt more than 99% pure, such as food-quality or water softener salt (often sold as "coarse solar salt"). Pentair and Jandy ask for at least 99.8% pure, evaporated, granulated, food-quality, non-iodized salt.
Avoid rock salt, iodized salt, and salt with anti-caking agents such as yellow prussiate of soda (sodium ferrocyanide), which can discolor fittings and surfaces. Pentair and Jandy also say not to use calcium chloride.
Water softener pellets are allowed by Hayward, Pentair and Jandy but take longer to dissolve, and Pentair warns they could damage plaster.
Public pools that follow the Model Aquatic Health Code must use pool-grade salt certified to NSF/ANSI 50 or 60, or registered with the EPA.

How to add it

Test the water first. Pentair notes that most pools already contain some salt.
Run the pump. Jandy says to turn its chlorinator's production down to 0% while you add salt.
Pour the salt straight into the pool, around the edge (Pentair) or into the shallow end (Jandy). Don't add it through the skimmer, main drain or surge tank, which can clog the filter or damage equipment.
Brush the pool floor so the salt doesn't pile up while it dissolves.
Let the water circulate for 24 hours before you retest. Pentair says not to take salt readings until then, and Hayward's display can take 24 hours to catch up.
Retest, then turn the chlorinator back on and set its output to hold your free chlorine level.

Add large amounts in stages. Because salt can only be removed by draining water, we suggest adding about half of a big dose, waiting 24 hours, retesting and working out the rest from the new reading. This is our advice rather than a manufacturer's rule, but it protects you from a wrong test reading.

New plaster: wait before adding salt. Hayward says 10 to 14 days, Jandy at least 4 weeks and Pentair at least one month. For a new vinyl liner, Pentair says to ask the liner manufacturer first. Salt raises the risk of corrosion around the pool: Hayward advises asking a stone specialist before using natural stone coping or paving next to a salt pool, and Pentair says to ask a pool professional about materials.

If your salt is too high

Hayward says the only way to lower salt is to partially drain the pool and refill with fresh water. Pentair's current guide says to dilute by draining some water and refilling, and its earlier IntelliChlor guide suggests doing this 1 ft (30 cm) at a time until the level is back below 4,500 ppm. Jandy says to backwash or partially drain until it is back in the 3,000–3,500 ppm range. The pool drain and refill calculator works out how much water to replace.

Keep chlorine and pH in range

A salt system is a chlorine generator, so the usual chlorine rules apply. Test free chlorine and pH at least twice a day, and more often when the pool is busy (CDC). The table shows the CDC's figures for home pools, the minimums the Model Aquatic Health Code sets for public pools, and what the salt chlorinator manuals ask for.

	CDC, home pools	Public pool code (MAHC)	Salt chlorinator manuals
Free chlorine, pool	At least 1 ppm; at least 2 ppm if you use stabilizer. Typical range 1–4 ppm.	Minimum 1.0 ppm without stabilizer, 2.0 ppm with it.	1–3 ppm (Hayward, Jandy); 2–4 ppm (Pentair)
Free chlorine, hot tub	At least 3 ppm	Minimum 3.0 ppm	3–5 ppm for spas (earlier Pentair guide)
pH	7.0–7.8	7.0–7.8	7.2–7.8
Stabilizer (cyanuric acid)	Not in hot tubs. Disinfection takes longer when it is present.	90 ppm or less	30–50 ppm outdoors, none indoors (Hayward, Pentair); 50–75 ppm (Jandy)

The MAHC is a model code for public pools that health departments can adopt; it is not a rule for home pools, but its minimums are a useful floor. The manufacturers' figures are what their equipment and warranties are designed around.

Pool chemical safety

Looking after a salt pool still means handling pH and other chemicals from time to time. The CDC advises:

Read the whole product label before each use and follow it.
Wear safety equipment such as goggles and gloves.
Never mix chlorine products with acid, which can create toxic gases, and never mix different pool chemicals with each other or with anything else. Open one container at a time and close it before opening another.
Only pre-dissolve a product if the label tells you to. Then add the chemical to water, never water to the chemical, which can cause a violent reaction.
Store each chemical separately in its original container, dry, below 95°F (35°C) and away from heat. Keep them secure and away from children and pets.

Keep swimmers out while you add anything by hand. The Model Aquatic Health Code only allows public pools to add chemicals by hand when no one is in the water, and it is a sensible rule at home too. Let the water circulate and check that chlorine and pH are back in range before anyone swims.

Common questions

How much does one bag of salt raise the salt level?: It depends on the size of the pool. One 40 lb bag raises a 10,000 gallon pool by about 479 ppm and a 15,000 gallon pool by about 320 ppm. One 20 kg bag raises a 50,000 litre pool by 400 ppm. The calculator shows this figure for your pool and bag size.
My salt reading is above the target. How do I bring it down?: You can't take salt out with a chemical. Hayward says the only way to lower it is to drain part of the water and refill with fresh water. To go from 4,000 to 3,200 ppm with water that has no salt in it, you replace 20% of the water: 3,000 gallons of a 15,000 gallon pool. An earlier Pentair guide suggests draining and refilling 12 inches (1 ft) at a time. The drain and refill calculator works out the amount and the number of rounds, including any salt in your tap water.
Why doesn't the answer match the chart in my manual exactly?: Each manufacturer rounds a little differently. For 10,000 gallons starting from no salt, this calculator gives 267 lb to reach 3,200 ppm, 284 lb to reach 3,400 ppm and 250 lb to reach 3,000 ppm, which match the Hayward, older Pentair and Jandy charts to the nearest pound. A pound or two makes far less difference than the accuracy of a salt test, which Pentair gives as within 500 ppm for its own sensor.
How much salt does a newly filled pool need?: Test it first: Pentair notes that most pools already contain some salt from the water supply and from chlorine products. If the reading really is 0, a 15,000 gallon pool needs 400.6 lb to reach 3,200 ppm, which is 11 bags of 40 lb, though only 0.6 lb of the eleventh is needed. A 50,000 litre pool needs 160 kg, exactly 8 bags of 20 kg.

Sources

Last checked and updated: October 31, 2026.