We add salt to our bleach AGP at the beginning of each season and have done for the past three summers. It softens the water and seems to make it more sparkly.

We put in enough to bring it to between 1,800 and 2,200 ppm, calculated rather than measured since I don't have salt strips. Some time in the middle of the swim season we might add a bag or so to replenish what's lost from splash out and refilling.

We use "solar salt" which is something like 99% pure, either Morton's or Diamond Crystal. We slit the bag open lengthwise and drop it into the pool where it takes a couple of days to fully dissolve. I don't know if there would be any harm to the liner if the salt crystals were just dumped in; by dropping in the entire bag we avoid contact with the liner.

Hope this helps.