go to the brew science section and use the spreadsheet there. 5.2 is a buffered product that may get some waters with some malts to the right ph, but not always. I find with my soft water that I get to the right ph for the brews I most frequently do with minimum additions of calcium chloride, epsom salts, and or gypsum. I've never needed to add acid or acidulated malt. With hard water, it "may" be necessary.
The color of the malt used has a huge effect on mash ph, so one size does not fit all.