In preparation for my imperial stout, I spent substantial time researching water chemistry. It's been on my homebrewing to-do list for quite some time, and if I was going to spend several hours outside in the dead of winter working on a big beer, I wanted it to knock my socks off -- no astringency, not too bitter, etc.
Madison has very hard water, but I'm not exactly sure what my end profile is since I have an Aquasana filter that supposedly leaves in the important minerals, but strips out the chlorine and other harmful chemicals. The line also goes through my water softener. So, for now, it's all kind of an experiment.
Although Beer Tools Pro does include the ability to adjust water chemistry, I opted not to use it because the program doesn't breakdown the necessary residual alkalinity range for beer styles or provide any information on the sulfate/chloride ratio -- which tells you if the beer is balanced, bitter, or malty.
I found dealing with pH the most confusing aspect. Mash pH and Residual Alkalinity.
Found Bobby from NJ's YouTube video to be helpful, https://www.youtube.com/watch?v=o1n7-RjEJEM#t=323. He recommended downloading the water calculator from EZwatercalculator.com. However, the updated version 3.0 on the website doesn't seem to contain some of the handy options found in version 2.0.