According to the science, calcium ions are needed in the mash water for the enzymes in malt to fully convert the starches. In theory, calcium deficient hot liquor should lead to lower conversion and efficiency. There must be some calcium in malt, but I don't know if it's enough? I take science on board, but to me, personally, brewing is not a science, but a craft, and in some ways, an art. But the bits science tells us are handy to know.
In any event, Sydney and Wollongong's water is soft enough for measures such as "a handful" of calcium carbonate and a pinch of calcium chloride, etc to produce the desired effect, which is "enough" calcium and a suitable pH for mashing, and a good mineral profile to enhance hop flavours. I don't know if microgram accurate scales for adding minerals would help me make better beer, but I doubt it.
Going back to David's analogy of the engineer with an axe, I don't find the analogy completely apt. We are making beer, which has some pretty huge tolerances, not highway bridges or skyscrapers. I'm not sure what Dave's chalk-line drawing, axe wielding engineer is building exactly, but if he's chosen those tools, he must think there is enough tolerance in his project. If not, it is doomed to failure.
I treat my brewery as more of a kitchen than a science lab, and although my beers will not always be identical, even when following the same "recipe", it's not a big deal to me, just as one pasta sauce might be more garlicky than the next. Recent infections and yeast issues aside, I enjoy all the beer I brew, such as the 1.080 IIPA that just found it's way into a cube. The malt and hop aroma coming out of the kettle was awesome. I just threw in "some" hops as the wort boiled. Yes, and a handful of calcium carbonate, a pinch of Epsom Salts and about a teaspoonful of CaCl.
