So having said that, I have a copy of Bru'n Water on my computer which I open periodically. It is just too complex and intimidating for me at this stage of my understanding. The reason I use EZ Water is because it is easy.
You may want to look at this: http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/
It is designed for easy entry but can do as little or as much as you expect from a water calculator.
as for getting 100 ppm, it depends on what you want to be at 100 ppm.
Yes, I've been looking at that. It looks very intuitive. I also enjoyed your podcast on the new water calculator on Basic Brewing Radio. You have been very informative there. I have listened to your two podcasts from 2011 with him on mash pH at least twice. Thank you!