Must have salts/acids?

[AlexKay]

It's what happens when chasing a pre-loaded "profile" that includes an HCO3 number, instead of building in what's needed. I've probably said this about a hundred times before, but no water recipe should ever start with any sort of HCO3 target. It should only be added if/when needed to raise pH.

I was nodding along vigorously in agreement, but then found this: https://www.homebrewtalk.com/threads/target-water-profile-for-munich-helles.573644/post-7426764.

Maybe modern brewers could add sodium lactate directly...? I'm not sure how easy it is to find food-grade salt, though.

 

[hilljack13]

The question I ask is why you need RO in the first place

I haven't had my water tested and at this point I don't plan too. I like to be hands on.
I do know that when my water dries it leaves a white residue, after being filtered.

 

[HighVoltageMan!]

For me it is because my alkalinity is 400 ppm, so when I brew a dark beer I add back filtered house water

This is by far the best way to add alkalinity if you need it. Baking soda brings sodium with it and pickling lime isn't perfect either. A good source of alkaline water (known levels) can be used to adjust pH up. If the mash drops too low use alkaline water or blend for sparging water.

It's better to come into the boil a little high on pH and dropping the pH with some acid than trying to raise it by adding alkalinity any where in the process with a water salt. At least that's been my experience.

I think it takes us way out of the "Beginners Beer Brewing" forum.

Probably. Getting fed with a fire hose can be overwhelming for some.