I just consulted with the contractor who put in the fiberglass lining years ago and at that time advised strongly against a salt system because of potential concrete damage. That is why I went with the copper ionization system I am unhappy with. I wanted his advice on how to get the copper out if I did decide to go with a SWG. He agrees with my plan to get it out with oxalic acid which I used regularly before the ionization system to keep metallic ions out of the water. He also indicated that salt is highly corrosive to copper pipes. Unfortunately all my underground pool plumbing is copper (above ground PVC). The pool was built in 1969 before PVC was allowed underground for pools here. Is this a big issue to be concerned about? If so, enough to scrap plans for a SWG?