Don,
I have been told that Sodium Thiosulfate will not break the chlorina/ammonia bond in chloramines, and if it did binding the ammonia still keeps it in the system for a while. If you use salt, it will release the ammonia. With Jackson changing out so much water it would be safer to use a product like chloramex, which actually oxidizes chlorine, chloramines and ammonia. It leaves you with clean water.
The information we got was from the water department and they said that if there are chloramines in the tap water then ST will not work.