Which water should I use?

My head is spinning from everything I've been researching about the best water for my betta. I've had him for about 3 months and he is in an unfiltered, heated 1 gallon cube. I had been using tap water conditioned with Prime for his water changes (100% once to twice a week). I recently tested my tap water and realized that the water straight from the tap has 1.0ppm Ammonia. I tested my Pur filtered water from the fridge door and it read .25ppm Amm so for the last couple of water changes I used that. I switched from Prime to Aqueon Betta Bowl Plus because it said that it adds trace elements...which I read are removed by the Pur filter.

Also, he may have some fin rot due to an injury when I tried to use a cup instead of a net to remove him a few weeks ago...I accidentally broke off a couple of fin rays with the edge of the cup. I started using aquarium salt and betta fix, but i haven't seen any change so today I did 100% water change and went back to my tap water treated with Prime and nothing else.

If someone could let me know which water option is better: the tap water with ammonia treated with Prime or the filtered, fridge water treated with Betta Bowl Plus. I worry about the ammonia in the tap water only being neutralized for 24 hours with the Prime. But is filtered water lacking important minerals?:hmm:

Thanks! It's amazing how this little creature has found his way into my heart. I just want to make sure that Mr. Fishburne (Lawrence) is healthy and has the best water I can provide.