I don't know if this will help or not, and I don't know if someone else mentioned this because I didn't read past the first page of the thread (my apologies if it has been suggested), but from what I understand, tap water is better than distilled water as it contains trace elements that the fish need that may otherwise be "removed" from distilled water; so long as you treat tap water with a good dechlorinator, like the aforementioned Prime, all should be good...