Not using salt

I have a Culligan Mark 812. It has 2 tanks. One large tank for salt and one smaller for something that sounds like it would be caustic. Would you have any pictures of the configuration of the piping for this system? The system seems to be working, but it isn't using any salt. I don't have the small tank hooked up. It does have one line coming from the water softener to the smaill tank but the other line is hanging open. I bought the house and the system was here but it wasn't hooked up and I hooked it up. It doesn't use any salt but it takes the rust out of the water. I do have well water. Any help you could provide will be appreciated.

Thanks,

Gary

This has the three tank set up?
Mark 812 , tank 18X36 salt, and then the little 6x33?

photos if you have any, also pm me if you would like.