I have to add my argued opinion here...
I never say anything because I know people swear by it, like religion, and it always starts wars, just like religion.
I have never, repeat never done a water change ever. I have added water to replace evaporated water using tap but my water has been checked and is pretty damn close to distilled water.
I have been doing this since I was 10. I watched my father struggle with his tanks and try his damnedest to get certain things out. Constantly...