Can someone with a bit of knowledge of chemistry help me with this, which is a matter of curiosity.
I have a salt water swimming pool. I put bags of salt into the water. The salt is sodium chloride. The chlorinator turns the chloride into chlorine, which keeps the water clean. So far so good. But what happens to the sodium? I asked Copilot, who told me that the sodium ions just “hang around”.
I am not satisfied with that answer. Ions do not just “hang around”. They react with something. Furthermore, I have to put bags and bags of salt into the pool every season. Big bags. That is quite a lot of chlorine, which is fine. It is also quite a lot of sodium.
For that matter, what happens to the chlorine, once it has done its work?
phenell 
Once the chlorine has finished killing germs or is broken down by sunlight, it turns back into chloride. It then finds a sodium ion, and they “reunite” to form NaCl once again. This is why you don’t have to add salt to your pool every day—the sodium is essentially recycled over and over.
That makes sense. Thanks, Colin. Australia Day here today. 38 degrees forecast, so swimming pool might well be welcome.