What is a salt water chlorinator?
Updated August 2026
A salt water chlorinator is a plumbed-in cell with electrified metal plates that turns dissolved salt into chlorine as pool water flows past it, so the pool sanitizes itself instead of being dosed by hand. The name misleads people. A saltwater pool is a chlorine pool; the chlorine is simply made on site, continuously, in small amounts, which is why the water feels softer and never smells like an open jug of shock.
Where it is
There are two pieces to find. The power supply is a wall-mounted box near the equipment pad with a display and an output percentage control. The cell is a short cylinder plumbed into the return line after the filter and heater, held by a union at each end and tied to the box by a heavy cable. Many cells use a clear housing, so a glance tells you whether the plates are clean gray metal or crusted white with calcium scale.
What it does
Inside the cell, low-voltage current splits salt and water into chlorine, which sanitizes the pool and then reverts to salt, so salt is lost only to splash-out, backwashing, and rain overflow. Target salinity is 2,700 to 3,500 ppm, about a tenth as salty as the ocean and below what most swimmers taste. Three things halt production: scale bridging the plates, water colder than roughly 60 degrees, and plate coatings that wear out after 3 to 7 years of duty. A tired cell is sneaky, because the display still reads 100 percent while free chlorine drifts toward zero and the steps start to green.
Maintenance
Inspect the cell at season open and every three months after that. Clean it only when you can see scale, using a 4-to-1 mix of water and muriatic acid for 10 to 15 minutes, never longer, since acid strips the coating the cell depends on. Hold pH at 7.4 to 7.6 (salt cells push pH upward) and cyanuric acid at 60 to 80 ppm so sunlight does not destroy the chlorine you just made. The filter and pump keep their own schedules; a chlorinator changes nothing about how often the filter gets cleaned. Plan on a new cell every 3 to 7 years, or roughly 8,000 to 10,000 hours of runtime.
What it costs to replace
A replacement salt water chlorinator runs $200–800 for a replacement cell, or $1,200–2,500 for a complete chlorinator system installed.
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Frequently asked questions
Is a saltwater pool actually chlorine-free?
No. A salt chlorinator produces the same chlorine you would pour from a jug, just steadily and in small doses. What changes is the ownership experience: no hauling tabs or liquid, fewer chemical spikes, and water that is easier on eyes and swimsuits because the chlorine level stays flat instead of swinging. You still test the water, still balance pH and alkalinity, and still shock the pool after heavy bather loads or a storm.
How much salt does a pool need?
Test salinity first, then add enough to reach the level your unit wants, usually 3,000 to 3,200 ppm. Starting from zero, a 20,000-gallon pool needs roughly 530 pounds, and each 40-pound bag lifts that same pool by about 240 ppm. Pour the salt across the deep end with the pump running, brush it toward the main drain, and retest after 24 hours. Avoid overshooting, since the only correction is draining and refilling part of the pool.
Why is my salt cell not producing chlorine?
Work through it in order. Check salinity, because low salt is the most common trigger for a no-output warning. Then look through the cell for white scale and clean it if you see any. Check water temperature next, since output falls off below 60 degrees and many units lock out entirely. Confirm the pump runs long enough to support the output percentage you set. If salinity, scale, temperature, and runtime all check out, the cell has reached the end of its life.
Does salt water damage pool equipment or decking?
At 3,000 ppm the water is mildly corrosive rather than aggressive, but over years it finds weak points: unsealed natural stone coping, galvanized fasteners, aluminum handrail anchors, and raw concrete in the splash zone. Rinse the deck occasionally, seal stone on the manufacturer schedule, and add a sacrificial zinc anode at the pad for $30 to $60. Heaters built in the last decade use exchangers that tolerate salt water fine as long as pH stays in range.