I know your messages is a little old, but I figured I would chime in anyway.

I obviously don't know her exact condition and your reasons for wanting her enviroment chemical free, but if she has an immune system problem I would not even consider anything except for chlorine (SWG being my suggestion, but any form will do). It is the only agent that will ensure the pool remains bacteria and virus free.

If you give her a bath in normal tap water she is already exposed to the amount of suggested chlorine in a pool (our tap water tests in @ 2ppm).

I am immunosupressed, have a SWG, keep the free chrlorine at 3ppm, and love it!

My doctors just have a blanket recommendation of no pool use at all, but if it is a private owned pool and you are sure you always maintain proper chlorine levels they think its a great idea. They have no restriction about swimming in the ocean though, shows you how well they feel most pools are maintained.