As I've referenced in a few posts lately I've been frustrated with lower than predicted mash pH's lately, probably linked to my switch from distilled to grocery store RO water for cutting my tap water. Tomorrow I'm going to brew a sorta-stout - 75% Breiss 2 Row, 15% flaked oats, 10% 500l debittered black malt (I presume caraffa III special or midnight wheat...guy at the shop didn't know). My thought was to try 100% tap water, unfiltered with just a campden tablet. I'll treat with lactic acid or baking soda (or maybe Chalk since I could use more calcium and have a decent bit of sodium already) if need be to hit a mash pH of 5.5-5.6. Flavor wise my goal is to brew a smooth, creamy, clean stout with some chocolate notes but as little harshness as possible.
But anyway, I wanted to see if you guys think my tap will be decent for this style or if I should dilute/add some minerals?
Ca: 43 (a bit low... but maybe workable?)
Mg: 13
Na: 42 (a little high?)
S04: 44
Cl: 92