I've been using baking soda with good results lately for dark beers. Martin says to be sure to keep Na levels under 50ppm, but if you use RO water, it's not hard to do that even on a dark beer. Agreed. I don't understand all the hate for baking soda. You don't have to use that much and it raises the pH and alkalinity enough with small doses. And it's cheaper and safer to handle than pickling lime...
I'm planning to start using distilled water because you can never really trust the water to even be RO on those machines. You just don't know how much they pay attention to keeping the filters up-to-date.
Yeah, I think if somebody were using their tap water which already had some sodium and then using baking soda for a dark beer, you could end up with overly high levels of Na. But with RO or distilled , I don't see it happening. I brewed a stout last winter where I mashed all the malts together, and the baking soda it took to get me to 5.5 pH gave me ~ 47ppm Na. Beer came out great - maybe the best stout I've made. As for the RO filter issue, I agree - so I bought a $20 TDS meter from Amazon to test the RO water from the store each time. Now I can buy RO water with confidence.
I should get one of those meters... I just might. I want to try using distilled once, see how I like it. I probably won't notice a difference, but who knows. Sucky thing about distilled is you have to buy the jugs and can't fill a 5 gallon deal like I do with RO. But then again, I walk to the store to get my water, so carrying all that water just isn't practical, which is why I've been using tap water lately. My tap water is decent, but I'd prefer to start from a blank slate and not have to worry about seasonal variations.