Water change questions

[Aquattro]

As far as I know, nothing but water evaporates. So top off is just returning to the previous state.

I haven't read Randy's stuff, it tends to take the fun out of this hobby for me. Apparently he likes adding Mg I'm happier doing large changes, and it's always worked, so it's what I do. I've seen nice tanks that do small daily, so I guess it can work fine. I dunno.