A salt pool is actually a chlorine pool. Chlorine is a salt on the periodic table. What’s happening is the pool is dosed with normal salt. Same stuff as on your fries. The salt content in that volume of water isn’t all the much. You shouldn’t be able to taste it unless you’re a Chef. A typical salt pool runs at 2500- 3200 ppm. About 1/300 th the salinity of a human tear.
The pool’s water runs through what’s called a cell at the filtration equipment. That cell changes normal salt to chlorine ( another form of salt) by a form of electrolysis. The chlorine goes right to work inside the pool plumbing and is partially converted back to normal salt by the time it gets back to the pool. It does this when chlorine oxidizes an organic ( virus, bacteria or what have you). That oxidation is the sanitizing process at work. What makes it back to the pool as chlorine, is a relatively low dose and just floats around waiting to oxidize an organic. It too, turns back to normal salt then. The whole process repeats. You’ll find more and more of these sanitizers at work in both public and residential pools these days. There are even units for above ground pools.
Any pool can be retrofitted with them but if the pool was previously a Bromine based sanitized one, the water needs to be dumped and refilled before using one.
Pros? The pool water is a little more stable and easier to keep that way. The water chemistry usually never gets in a mess because there are fewer additional chemicals being required. Salt generated pools tend to be more swimmer friendly than any other sanitizing
It’s basically a recycling system. Pretty enviro friendly compared to other sanitizing systems.
Cons? Initially expensive. They’re pricey but they save chemical costs and energy over time. They eventually pay for themselves and then provide sanitizing at next to no cost at all with money saved.
Other cons are that you need to watch your stabilizer levels more carefully since cyanuric acid is no longer being added to the pool via stabilized pucks in a residential pool. It should be checked 4 times a year at a pool shop with a water sample. You also need to monitor the salt content. Most units will have an LCD display that will warn you if the salinity is too low or high as well as having a sensor that will give you an accurate reading of the salt content so you’ll know approximately how much salt to add or water to dump (if you over salted the pool) to bring the level within the unit’s operating requirements. The cost of the salt is minimal. About 20 bucks for a 50 pound bag and most sand filtered residential pools will only use two bags maximum per season once they’ve been initially salted. A D.E. or cartridge filtered pool will use even less. Perhaps only a bag if the pool was drained to winterizing level the previous fall.
Another con, if you want to call it that, is that these units work only in certain water temps. Too cold (less than 65F for many) and the unit may refuse to start. You probably won’t be swimming but the unit won’t be making chlorine until the water warms up.