Using the Tilt hydrometer, I began to experience what I think you’re describing: ‘blips’ in the log (possibly indicating yeast multiplication activity) without visual airlock activity (indicating CO2 production) at both the beginning and end of fermentation.
Seeing that, I began to define ‘lag time’ as the straight line before the first ‘blip’ or two. My observation does not rely on airlock activity.
I’ve noticed that if I pitch at the higher end of the mfr suggested rate, I see a shorter ‘lag time’ (straight line on the log as I’ve described it above) than if I pitch at a lower rate. It seems others have noted the same thing I have (as cited above).
I also notice a faster fermentation and better AA. Of course, this is anecdotal based on my experience. I used to complain that 34/70 would take 10-14 days to plod along to finish. Now, I am getting 5-7 days however, I am using it just slightly higher (60*F) than the recommended temp range (53-59*F) which probably doesn’t hurt the speed.
I guess I fall into the camp Brülosophy describes in the article I linked to: “Despite the fact tasters were unable to reliably distinguish between the underpitched and overpitched beers, there were some differences. For example, the underpitched batch took nearly 2 days longer to show signs of active fermentation compared to the overpitched batch, which may be viewed by some as reason enough to pitch more yeast...”
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