This is exactly what I would have suggested. My citric acid is about as fine as pickling salt and it’s add a pinch, stir, taste again after a minute. Probably end up with 2ish small pinches per gallon at a guess but I always go slow.
At this moment I’m eating one of my last frozen quarts of last year’s soup. I’ll make this year’s in the next week or two.
As crossover with the salt thread, For me, getting the salt right is one of the key parts of the soup. It always takes much more than I expect.
I’m starting with a brined turkey, so I don’t add any salt until near the end. After I’ve added the last ingredient (noodles or something), I’ll start adding salt at about a tablespoon at a time (to several gallons), and then tasting. Eventually it will taste right. That is where I stop.
I have no idea how much that ends up being per serving. That’s the amlodipine’s job to worry about.