One of the things I've found is that with low alkalinity, it appears you have great liquor for pale ales and lager. For pale ales you need to add gypsum and calcium chloride, and you can make great/good/passable pale ales ... Follow the guidance for lager though, and I've fallen flat on my face ... WTF!! The brewers in Plzen have softer water than we do, it's virtually distilled! How do they get away with it? It took a trip to Eastern Europe to resolve the issue, and assisting at some small 'craft' breweries over there, and the secret ... They add calcium!! Mostly calcium chloride, but I've seen gypsum tucked away as well. I've done a few test mashes, and pils malt and low calcium levels (low alkalinity obviously) pH stays stubbornly high ~5.7, add 60ppm calcium and the pH can drop as low as 5.4, up to 100ppm and the pH drops to 5.2. ... When you have 'crystal' malts in the mix then you can get away with lower levels of calcium to get the pH in the ball park, but personally
I would never go below adding an additional 60ppm calcium.
Raising alkalinity for my malty dark beers is a whole 'nother story