In the cost vs time, still nothing beets chlorine but a salt system. (Which is still chlorine in the end.) But as far as I know, you can not switch from chlorine to the polymer with out a flush of the system and complete water replacement.
Also, there are a few more things you have to do to a pool other than chlorine to keep it fresh and clean. If you have serious concern and still want to use the pool, I would just buy your own 25k bin of Calcium Hypochlorite and dump it in your self. Go in with your neighbors, with the number of pools in LOS, it cant be too expensive.