I chose to help with removing a Miata engine on Saturday, so no brewing this weekend. The weather this weekend was really frightful anyway, around 20 degrees during the day and in the teens or lower at night. I did rack the Boathouse Amber to secondary on Sunday though, and encountered another batch that didn’t ferment out fully. I made a point to ferment at a lower temperature this time (66 instead of 68 to 70), so that could have accounted for it, but I managed to aerate the wort a lot more, since I used the anti-foam agent. All the conditions are right for the yeast - proper wort pH, proper temperature, aeration, so it’s mystifying. I think I’ll have to add yeast nutrient not only to the starter next time, but also to the wort boil. Perhaps that is the problem. Gravities after one week for the amber were 1.024 for the London ale, and 1.025 for the Dry English. That’s just too high for a beer of starting gravity of 1.057.If it’s not the yeast nutrient, perhaps it’s the weather outside. Strangely enough, over the years I have noticed that fermentations seem more active during the summer than in the winter, even though the temperature inside the fridge is the same year-round. Could it be something less obvious, like barometric pressure or humidity? I certainly haven’t seen any research on yeast fermentations to indicate so. I’ll pay particular attention to the yeast nutrients next brew and see the effect.