Do you use Bru'n Water? I just started using it to build from RO, and it really is an amazing tool. Contains lots of profiles to start from and makes it easy to design mash and sparge builds and predict pH. If you haven't tried it, get the free version from the Bru'n Water website and start there! (It's an Excel spreadsheet, and I run it successfully on the Excel app for Android if you don't have a PC.)