So they're chlorinating to get rid of the sulphur and using the chlorine as and oxidizer to help remove the iron. In my opinion, the carbon filter should be in front of the softener or better yet, an iron filter in front of the softener. That takes the iron out of the water before it goes to the softener. The iron will foul the carbon over time, so that's where an iron filter would have been better. If the chlorine is adjusted so it's very minimal, it wouldn't do any damage to the softener.