Ultra-Swim works for me.

I was swimming 5 days a week for a while and ended up with brassy, crunchy, hair from the chlorine (and I have dark hair).

Ultra Swim helped a lot.

Also, the tip about wetting your hair before you get in the pool is good. That helps. Hair is somewhat porous, so saturating it first with non-chlorinated water helps to keep the chlorine out.