What exactly happens to the Chlorine...

[doncaruana]

First - sorry if this has been answered (I didn't find it) or doesn't belong here...

Being the geek that I am, I'm trying to make sense of exactly what goes on during the whole chlorine process and shocking.

From the top...
I put chlorine in the pool
The chlorine finds "stuff" in the pool...sweat, microorganisms, whatever (?)
The chlorine does something to the "stuff"...what? For some of it, it combines with it to become chloramines. These don't sanitize anything and cause that distinctive "chlorine" smell.
Some of my chlorine gets broken down because of the sun. Where does it go?
When I shock, all that extra free chlorine does what to the chloramines? And where does all that chlorine go?
And, finally, and this may have been answered with the above questions, but, during normal operation, how does the chlorine get recycled so that my SWG doesn't eventually (and fairly quickly) just run out of NaCl to break down?

Thanks for tolerating me.

 

[chem geek]

I believe this post has most of the answers you are looking for. During the day, most chlorine is usually broken down by sunlight to chloride salt. The chlorine that combines with ammonia to form monochloramine that registers as Combined Chlorine (CC) continues to get oxidized by chlorine to nitrogen gas and the chlorine becomes chloride salt (see this post for more technical details for chlorine oxidation of ammonia and this post for some speculation on chlorine oxidation of urea but where the chloramines get further oxidized as with the ammonia model). With an SWG system, the chloride salt gets converted back to chlorine (hypochlorous acid or more accurately hypochlorite ion after combining with the hydroxyl ions from the other plate). So with an SWG, the chlorine is recycled except for a small amount of hypochlorous acid that outgasses and a small amount of combined chlorine that gets filtered out and the amount of chlorine and chloride salt that get diluted by splash-out, carry-out, backwashing, etc.