First off to all those who struggle with water chemistry, I hear ya. I struggle as well and I am a MS chemical engineer with MS in environmental engineering with course in water chemistry as part of that. I need to break the text books out.
To answer the question, for hazy oatmeal IPA I target Ca ppm ~110, sulfate/chloride ratio 1.4. I play around with sodium chloride addition to sweeten after brewing by taste test. But I keep it less than 200 ppm as NaCl. My target is around 110 ppm as NaCl. I adjust the mash pH with lactic acid to 5.3 to 5.5 after 10 min in mash. I want to play around someday with the sulfate to chloride ratio bump it higher. No hops in boil all whirlpool and dry. IBU high 20s calculated.
I moved brewing to a second home with well water as opposed to surface water from POTW at my home. The well water is alkaline and has to be diluted with distilled water. If I don't dilute, I have to add too much lactic acid. Thinking about ordering HCl so I can titrate for direct alkalinity measurement as well as adding instead of lactic acid. Warning don't use concentrated strong acids like hydrochloric or sulfuric acid unless you have experience. I miss my laboratory and equipment. Glassware is sooooo expensive!