Salt chlorine generator (SWG)
Also called: SWG, salt system, salt water chlorinator, salt water pool.
A salt chlorine generator (SWG) runs a low-voltage current through salt dissolved in the pool water and produces chlorine, the same sanitizer (hypochlorous acid) that comes out of a jug of liquid chlorine. A salt water pool is a chlorine pool that makes its own chlorine.
Why it matters
Salt is not a sanitizer. It is the raw material, and with the cell off a salt pool stops being sanitized. The perks are real: steady automatic dosing, softer-feeling water, no jugs to haul. It is convenience, not chemical-free. You still test, run CYA higher at 60–80, and buy muriatic acid, because pH still climbs, mostly as carbon dioxide escapes the water. The cell only makes chlorine while the pump runs, and the output percentage is a share of pump run time. On an above-ground pool, read the pool's warranty first: some makers void it for any salt system.
In numbers
Trouble Free Pool's method for a salt pool: with CYA at 70–80, target free chlorine of 5–10 ppm and never below 5, then test at the same time each day and adjust the cell's output or the pump run time until it holds.