Originally Posted by bhughes
Here are a few questions:
1. Does a higher gravity beer have a longer primary fermentation phase than a lower gravity beer with all other factors being the same?
2. If this second batch was not aerated as much as the first batch, would that cause the primary phase to take longer?
3. Do cooler temperatures slow down the fermentation process?
4. Is it better or worse either way if the primary phase takes longer?
1. Sure, if you have the exact same number of yeast cells. More sugar, more time needed to ferment it. In practice there are always variables that make each fermentation a little different.
2. It's possible. The yeast use O2 in the growth phase of fermentation as they produce more cells. Less O2 would slow the growth of cells.
3. Yes, the yeast will work slower at lower temperatures, but it will also help reduce ester development and make a "cleaner" beer.
4. I don't think it really matters. I primary everything about 4 weeks.