The one-sentence version
A salt water pool is a pool that manufactures its own chlorine.
That clears up the most common misunderstanding straight away. Salt does not clean the water. Chlorine does. The salt is the raw material, and a piece of equipment called a salt chlorine generator turns it into chlorine a little at a time, all day, for as long as the pump is running.
The cycle, step by step
- Salt goes in. Pool-grade salt, which is nearly pure sodium chloride, is poured into the pool and dissolves. The target is usually around 3,200 parts per million.
- Water circulates. The pump draws water out, pushes it through the filter and the heater, and then through the salt cell on its way back.
- The cell does its work. Inside the cell are coated metal plates carrying a low-voltage direct current. As salty water passes between them, electrolysis splits the salt and produces chlorine.
- Chlorine sanitizes. That chlorine dissolves at once as hypochlorous acid, the same active sanitizer you get from any pool chlorine. It kills bacteria and algae and breaks down what swimmers leave behind.
- Chlorine becomes salt again. Once it has reacted, it reverts to chloride. The salt is back in the water, ready for another pass.
Because the salt is recycled, very little is consumed. You are not feeding the pool salt the way you would feed it tablets.
The parts of a salt system
There are only two components that a traditional pool does not have.
- The cell
- A short section of pipe housing the plates. Water flows straight through it. This is where the chlorine is made, and it is the part that eventually wears out.
- The control unit
- A box on the equipment pad that powers the cell and lets you set how much chlorine it produces, usually as a percentage. Most also display the salt level and flag faults.
A flow sensor makes sure the cell only runs when water is moving. Many systems reverse the current every few hours, which helps shed mineral scale from the plates.
How to choose and size one is covered in our guide to salt water pool systems.
How salty is it, really?
| Water | Approximate salt level |
|---|---|
| Fresh drinking water | Under 500 ppm |
| Salt water pool | 3,000 to 3,500 ppm |
| Human taste threshold | Roughly 3,500 ppm and above |
| Seawater | About 35,000 ppm |
A salt water pool sits at or just below the point where most people begin to notice a taste. It will not sting a cut, crust on your skin or leave a white line on a swimsuit the way the sea does.
What a salt water pool still needs from you
The generator handles one job: making chlorine. Everything else about water balance is unchanged.
- pH. The process that makes chlorine nudges pH upward. Expect to add a little acid regularly to hold it between 7.2 and 7.8.
- Stabilizer. Cyanuric acid shields chlorine from sunlight. Without enough of it, strong sun destroys chlorine faster than the cell can make it.
- Alkalinity and calcium. Kept in range to protect the pool surface and to limit scale on the cell.
- Run time. No flow, no chlorine. The pump has to run long enough each day for the cell to keep up.
The routine is set out in the maintenance guide.
How that compares with a traditional pool
A traditional pool reaches the same end by a different road. Chlorine is bought, stored and added on a schedule, and the level in the water rises and falls between doses.
The salt approach trades that routine for a higher equipment cost and a few material considerations. If you are deciding between them, the full comparison is in salt water pool vs chlorine pool, and the trade-offs are summed up in benefits and drawbacks.
