Converting a pool to salt water
Converting a 15,000-gallon pool with no salt in it to 3,200 ppm takes about 401 lb of pool salt (eleven 40 lb bags).
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
On this page (7 sections)
Before that, pick a cell rated above your pool size, and plan to raise stabilizer (CYA) to 60–80 ppm if you follow Hayward's guidance.
The calculator starts from a salt reading of 0. Test first: most pools already hold some salt from tap water and from chlorine itself, and Pentair's manual tells owners to test before adding any.
Is your pool a good candidate?
Most residential pools can run on salt, but check these before you buy anything:
- Surface cure. New plaster needs time before salt goes in: Hayward says 10–14 days, and Pentair says at least one month. Pentair suggests a spacer ("pass-through") cell for the first 30 days so construction debris does not reach the new cell. For a new vinyl liner, Pentair says to ask the liner manufacturer first.
- Natural stone. Hayward recommends consulting a stone specialist about sealing and care before running salt next to natural stone coping or decking.
- Equipment and metals. Check the manuals for your heater, pump, lights, and any metal rails or ladders for salt compatibility. Pentair specifies no copper, iron, or manganese in the water.
- Season length. Cells stop in cool water (AquaRite below 50 °F, IntelliChlor below about 52 °F). In a short, cool season, you will still add chlorine by hand for weeks.
- Your chlorine habits. If you often miss doses, steady production is the biggest benefit. If your chlorine use is low and you enjoy the routine, the math may not favor switching. Compare with salt water vs chlorine.
Cell sizing
Cells are sold by the largest pool they are rated for, and some manufacturers also publish pounds of chlorine per 24 hours. Hayward's AquaRite cells are rated for 15,000 (T-CELL-3), 25,000 (T-CELL-9), and 40,000 gallons (T-CELL-15). Pentair's IntelliChlor line runs IC15, IC20, IC40, and IC60, and its guide lists production of 0.60, 0.70, 1.40, and 2.0 lb per 24 hours of pump time at full output.
Pounds per day mean little until you turn them into ppm for your pool. Here is what those Pentair ratings add at 100% output, by pump hours:
| Cell (rated lb/24 h) | 15,000 gal, 8 h pump | 15,000 gal, 12 h pump | 20,000 gal, 8 h pump | 20,000 gal, 12 h pump |
|---|---|---|---|---|
| IC15 (0.60) | 1.6 | 2.4 | 1.2 | 1.8 |
| IC20 (0.70) | 1.9 | 2.8 | 1.4 | 2.1 |
| IC40 (1.40) | 3.7 | 5.6 | 2.8 | 4.2 |
| IC60 (2.0) | 5.3 | 8.0 | 4.0 | 6.0 |
Our arithmetic: ppm per day = lb per 24 h × (pump hours ÷ 24) × 453.6 g × 1,000 ÷ liters of water. It assumes the published rating. Real output falls with age, low salt, and scale.
Compare that with how much chlorine your pool uses on a hot, busy day (test FC at dusk two days in a row). If the cell needs 100% output and long pump hours to keep up in July, it is undersized. A cell with spare capacity lets you run a lower output percentage or fewer pump hours. Pump turnover time is in the run time calculator.
Start-up salt dose
Salt needed = (target ppm − current ppm) × gallons × 8.345 ÷ 1,000,000 pounds. If your water already has some salt, you need less:
| Pool size | From 0 ppm | From 400 ppm |
|---|---|---|
| 10,000 gal | 267.1 lb (7 × 40 lb) | 233.7 lb (6 × 40 lb) |
| 15,000 gal | 400.6 lb (11 × 40 lb) | 350.5 lb (9 × 40 lb) |
| 20,000 gal | 534.1 lb (14 × 40 lb) | 467.3 lb (12 × 40 lb) |
| 25,000 gal | 667.6 lb (17 × 40 lb) | 584.2 lb (15 × 40 lb) |
| 30,000 gal | 801.2 lb (21 × 40 lb) | 701.0 lb (18 × 40 lb) |
Bags rounded up. Use your cell's own target if it differs; the salt calculator handles any target and bag size.
Buy salt that is at least 99% sodium chloride with no iodine, yellow prussiate of soda, or anti-caking agents (Hayward). Pour it into the pool with the pump running, brush it until it dissolves, and wait about 24 hours before testing again. Adding a second round before the reading settles is the most common way to add too much salt, and salt comes out only by draining.
Adjust CYA and TA targets
Stabilizer. Hayward recommends CYA of 60–80 ppm for salt pools; Pentair's guide keeps 30–50 ppm. We follow the higher band with a free chlorine minimum of 5% of CYA, which suits a cell that feeds chlorine all day. Raising CYA by 30 ppm takes about 3.8 lb of stabilizer in 15,000 gallons and 5.0 lb in 20,000 gallons. The stabilizer calculator gives exact amounts. Stabilizer only comes down by draining, so add it in steps and retest.
Alkalinity. Many salt pools settle best at TA 60–90 ppm, because lower alkalinity slows the pH climb that salt cells are known for. Lower TA gradually with acid and aeration, and check your saturation index (LSI).
First month
- Day 0: balance the water first. Pentair's quick start says pH 7.2–7.8, calcium 200–400 ppm, and alkalinity 80–120 ppm before start-up, then superchlorinate with an outside chlorine source.
- Day 1: add salt, circulate for 24 hours, and test salt with two methods.
- Days 2–14: start the cell near 50% output (Hayward's suggestion), test FC every few days, and adjust. It usually takes two or three changes.
- Weeks 2–4: watch pH. Once you see it drifting up, start small, regular acid doses.
- End of month 1: test CYA, TA, calcium hardness (CH), and salt again, then settle into the salt pool maintenance routine. Pentair's self-cleaning cycle changes from 2 to 3 hours after the first 192 hours. This happens automatically.
Targets for every other parameter are on the chemistry chart.
FAQ
Should I get a salt water pool?
Consider it if you want steady chlorine without daily dosing, your season is warm enough for the cell to run, and your coping, equipment, and budget can handle salt and a replacement cell every few years. Stick with added chlorine if your use is low, your season is short and cool, or you have natural stone you do not want to reseal.
How much salt do I need to convert my pool?
About 267 lb per 10,000 gallons to go from 0 to 3,200 ppm: 401 lb for 15,000 gallons and 534 lb for 20,000. Test first and subtract the salt already in your water, and use the target in your cell's manual.
Sources
- Hayward, AquaRite manual (cell models by pool size, salt type, plaster cure, stabilizer 60–80 ppm, start-up output): PDF
- Pentair, IntelliChlor SCG Installation and User's Guide, P/N 520589 Rev. R (2023) (models and production, plaster, vinyl, metals, CYA): PDF
- Pentair, IntelliChlor Quick Start Guide and Tips, P/N 520943 Rev. D (2023): PDF
- Hayward, How much salt do you add (10,000 gal cross-check): hayward.com