The pool in my back yard has a mechanism that generates chlorine by electrically separating chlorine out from salt that you dump in. If I remember my chemistry correctly when you put salt in a solution the sodium and chlorine separate into ions, so I guess all you need to do is add an electron back to the chlorine and you’re good to go. You’ll see these advertised in real estate flyers as “salt water pools” but it’s not salty like the ocean. Ocean water is around 35000 ppm (parts per million) while the pool only needs about 3000 to function. I love it because a 40 lb bag of pool salt costs about $6 and I put in one about every 3-4 months.
The salt water pool presents its own maintenance challenges. This summer I’ve had a hard time keeping the chlorine level up in the pool. I’ve been leaving the salt generator up at full blast and there’s never more than 1 ppm. It’s also been a blazing hot summer and I’ve had to add about a half inch of water every week, I don’t know if that’s relevant. I started testing more than pH and Chlorine with some test strips that have extra tests on it and the alkalinity is also real high. Yesterday I pumped about 6 inches of water out of the pool and filled it back up from the tap. About 5 hours later the chlorine level had shot up to 2 ppm.
I think what was happening was that the evaporation of the water was causing a build up of something that was preventing the salt generator from doing its thing. Reading around on the interwebs I found that evaporation will cause the hardness of the water to go up because the minerals don’t evaporate out, this or the collection of something else that doesn’t evaporate out must diminish the salt generator’s efficacy. Hope this helps another salt pool owner out.