Just wanted to mention, that salt is left behind when water evaporates. It won't evaporate out, if you decide that you want to remove it, water changes will be needed. Personally, I would bet that the salt went along way in helping the fish recover from the bacterial infection. Might have been good luck that you used the softened water? I don't know much about water softeners, but have always heard that they don't mix well with fish tanks.