Re: Laundry drain backing up
You must be experiencing other draining issues than just the laundry drain. Roots in the main shouldn't affect just that one laundry drain pipe. It may be possible there are other issues with the drain lines in the home.
For dealing with roots the most effective way I know is to remove the tree.I don't know about the pool chlorine and salt idea since salt ( NACL)is sodium-chloride and i don't know if it would be a good idea to have this corrosive solution sitting in cast iron pipes.