Oh, it's absolutely not equipment related. Good thought though! (One might suspect you'd had a career involving troubleshooting systems... oh you did. Thanks for your service.) As noted, I keep good records. I know what a normal fermentation record looks like, and what's interesting is that the same yeast, in the same conditions, behaves differently in first and subsequent generations. Which, with respect to this parameter, does not occur with liquid cultures, IME. I have a fairly small number of data points, but enough to establish a clear pattern, raise a red flag, and suggest a hypothesis, or I wouldn't have started this thread; I haven't found a confirmed exception. Before I decided to explore for myself the possible advantages of dry yeast, I'd noticed plenty of mentions on the forum of tartness with dry yeast. I realized that my habit of monitoring pH, and reusing yeast, might have peeled back a layer others hadn't noticed. What I lack is the ability to identify a likely mechanism, and remedy. Forgive me if I'm rambling. The practical assessment of product is going well.