The water from the store didn't have chlorine in it? I really don't think conditioned water would hurt him but you could use half of water from the store and half of the conditioned water to be safe, to start out with.
My betta has fin rot so I got AQ salt. I want to start doing the 100% water changes daily with the salt. However, I usually use water from the water store, and it's really pure, and Neptune seems happy with it. How would I get him used to the conditioned water so I can start his treatment? Or should I just start doing it immediately. Actually, I just cleaned his tank and I'm about to put water in,so which one?