Hadn't thought of that. So, a tiny mash, to scale, test the pH and go from there?
Sent from here, because that's where I am.
Yep!
I'd try something like brewer's friend's water chemistry spreadsheet if you don't have bru'nwater handy (it's been dead nuts accurate for me) to get you close, and then a test mash to ensure the correct additions and mash ph- then brew!