Pommy Matt
Member
- Joined
- 4/6/11
- Messages
- 24
- Reaction score
- 3
Hi all,
Fairly new to AG, brewed my 7th batch last Thursday, which was also my first double batch. Roughly the Northern Brewer SNPA clone, brewed a bit lighter and with a bit of added wheat.
I ended up with 48L of 1046 wort after hitting all my numbers pretty well. After rapid chilling to 20C, 27L of this went into a 30L fermentor, and the remaining 21L into another. Both fermentors put into a single large fridge set for 15C. Yeast was the slurry (US05) from a pale ale that I racked to secondary on the same morning as the brew, and each fermentor got the same amount - a schooner (not too scientific, I know).
So the interesting thing about all this is that today I checked the SGs of both, and the larger batch is sitting at 1028 (pretty slow), and the smaller batch is at 1012. Wort temp of both has been a more or less constant 18C.
The only differences I can possibly see are:
1. the amount of yeast pitched (relative to batch size) - this would have been higher for the small batch by about 25%.
2. Possibly the levels of aeration could have been different, since the aeration took place in the fermentor.
3. outsider - the smaller batch got filled second, and had a lot more trub than the 27L batch.
I'm not particularly worried about this, just thought it was an interesting observation. If anyone can think of any other reason for the difference (infection?) then that would be interesting. Otherwise, it is kind of eye opening to me that such seemingly small changes could make such a big difference to fermentation speed.
matt
Fairly new to AG, brewed my 7th batch last Thursday, which was also my first double batch. Roughly the Northern Brewer SNPA clone, brewed a bit lighter and with a bit of added wheat.
I ended up with 48L of 1046 wort after hitting all my numbers pretty well. After rapid chilling to 20C, 27L of this went into a 30L fermentor, and the remaining 21L into another. Both fermentors put into a single large fridge set for 15C. Yeast was the slurry (US05) from a pale ale that I racked to secondary on the same morning as the brew, and each fermentor got the same amount - a schooner (not too scientific, I know).
So the interesting thing about all this is that today I checked the SGs of both, and the larger batch is sitting at 1028 (pretty slow), and the smaller batch is at 1012. Wort temp of both has been a more or less constant 18C.
The only differences I can possibly see are:
1. the amount of yeast pitched (relative to batch size) - this would have been higher for the small batch by about 25%.
2. Possibly the levels of aeration could have been different, since the aeration took place in the fermentor.
3. outsider - the smaller batch got filled second, and had a lot more trub than the 27L batch.
I'm not particularly worried about this, just thought it was an interesting observation. If anyone can think of any other reason for the difference (infection?) then that would be interesting. Otherwise, it is kind of eye opening to me that such seemingly small changes could make such a big difference to fermentation speed.
matt