What changes with salt, and what does not
Salt water pool maintenance is lighter than looking after a traditional pool in one respect: you are not adding chlorine by hand every week. The salt system does that.
Everything else is the same. Water still needs to be tested, balanced, filtered and kept moving. Owners who treat a salt pool as self-managing are the ones who end up with cloudy water in August.
The numbers to aim for
| Measure | Typical target | Why it matters |
|---|---|---|
| Free chlorine | 1 to 3 ppm | Keeps the water sanitary |
| pH | 7.2 to 7.8 | Comfort, and how well chlorine works |
| Salt | 2,700 to 3,400 ppm, ideally near 3,200 | The cell needs it to make chlorine |
| Total alkalinity | 80 to 120 ppm | Steadies pH |
| Calcium hardness | 200 to 400 ppm | Protects the finish, limits scale |
| Cyanuric acid (stabilizer) | Often 60 to 80 ppm for salt pools | Shields chlorine from sunlight |
These are common industry ranges. Always check the manual for your own salt system, because the acceptable salt range and recommended stabilizer level vary by manufacturer.
Every week
- Test free chlorine and pH.
- Adjust the generator's output up or down if chlorine is outside the range.
- Lower pH if it has crept above 7.8. Muriatic acid is the usual choice, added in small doses with the pump running.
- Empty the skimmer and pump baskets, and brush steps, benches and the waterline.
- Glance at the control unit for warning lights.
Every month
- Test the salt level with strips or a meter and compare it with the control unit's reading.
- Test total alkalinity, calcium hardness and stabilizer.
- Check the filter pressure and clean or backwash when it has risen by the amount the manufacturer specifies.
- Look over nearby stone and metal for early signs of salt wear.
Getting the salt level right
Salt is not consumed by the generator. It leaves the pool only with water: splash-out, backwashing, a leak or a partial drain. Rain and fresh top-ups dilute what remains.
The arithmetic for adding it is straightforward. Roughly 83 pounds of salt raises 10,000 gallons of water by 1,000 ppm.
| Pool volume | Salt to raise by 500 ppm | Salt to reach 3,200 ppm from zero |
|---|---|---|
| 10,000 gallons | About 42 lb | About 267 lb |
| 15,000 gallons | About 63 lb | About 400 lb |
| 20,000 gallons | About 83 lb | About 534 lb |
| 30,000 gallons | About 125 lb | About 800 lb |
Use pool-grade salt, which is at least 99 percent pure sodium chloride with no anti-caking additives. Pour it into the shallow end with the pump running, brush until it dissolves, and wait 24 hours before retesting. Add in stages. Too much salt can only be fixed by draining water.
Looking after the salt cell
Every three months or so, remove the cell and hold it up to the light. Clean plates look like bare metal. White, flaky deposits are calcium scale, and they reduce output.
- Switch off power to the system and the pump.
- Unscrew the unions and lift the cell out.
- Rinse with a garden hose first. That is often enough.
- If scale remains, soak the plates in a diluted acid solution mixed to the manufacturer's instructions, for no longer than they advise. Wear gloves and eye protection, and add acid to water, never the reverse.
- Rinse thoroughly and refit.
Clean only when you can see scale. Acid removes a little of the plate coating each time, so unnecessary cleaning shortens the life of the cell.
When to add chlorine by hand
A generator is built for steady production, not for sudden demand. After a heavy storm, a pool party, or the first sign of green, raise the chlorine level quickly with the boost setting or with liquid chlorine. Liquid chlorine is also the stopgap when the water is too cold for the cell to run.
Through the year
This is the calendar for a climate with a real winter. In warm states the pool stays open, and the summer line applies for most of the year.
- Spring opening
- Balance the water and add chlorine by hand until the pool warms past the cell's cold-water cutoff, usually 50 to 60 degrees. Then test salt and top up.
- Summer
- Strong sun eats chlorine. Keep stabilizer in range and let the pump run long enough for the cell to keep up.
- Autumn
- Leaves and cooling water. Skim often, and expect the cell to switch off as temperatures fall.
- Winter closing
- Balance the water, lower the level if required, drain and protect the plumbing and equipment, and drain or remove the salt cell so it cannot freeze.
If something looks wrong
- If chlorine is low and the salt reading is low
- Add salt in stages and retest.
- If chlorine is low and salt is fine
- Check stabilizer, pump run time and the cell for scale.
- If the water is cloudy
- Test pH and chlorine, clean the filter and run the pump longer.
- If white flakes appear in the pool
- Scale is shedding from the cell. Check calcium and pH, then inspect the cell.
- If stone or metal near the water is deteriorating
- Rinse it regularly, seal the stone and fit a sacrificial anode. See benefits and drawbacks.
If you are still at the planning stage, a great deal of this is made easier by design: good circulation, the right materials and a correctly sized system. That is what we think about when we draw a salt water pool.
