As a completely new person to the forum, and new to espresso in general, this post: Good references on water treatment for coffee/espresso has been extremely helpful. I managed to not bookmark it, and then was struggling to find it again. I would recommend that you put this in the reference list as a great overview and a great visual representation of what hundreds of other threads are discussing.

It's the first link in the FAQs and Favorites sticky right above your thread under "Required Reading".

Well then, I genuinely thought I went through all of those and couldn't find it. My bad!