split batch fg

[Aggie10]

I did a IPA split batch (one hot wort split into equal halves, identical everything) and I have taken a FG from one of the halves and it is close to predicted FG. Taking second reading soon to confirm fermentation complete but do I have to measure FG in the other half as well, or safe to assume it will be same? FYI - at day 14 now.

 

[ncbrewer]

I would check both, but that's just me - assuming you're kegging. If you're bottling, I would definitely check both - for safety reasons.

 

[HB_ATL73]

Well the wort is the same but what about yeast? ferm temp? I would take the measure on both to make sure both are complete

 

[RM-MN]

or safe to assume it will be same?

It is never safe to assume that the two would be at the same point in their fermentation. Slight differences in the volume, the pitch rate, temperature, phase of the moon, anything can make the yeast act differently in two seemingly identical batches. Always test.

 

[SRJHops]

While I can't argue with taking readings from both, it's worth considering the risk of adding oxygen (and the risk from infection, which is low). Lately I've been wondering about the need to take a lot of FG readings...

If you can purge your carboy with Co2 then the risk of adding oxygen is lower, of course. If you can't, I might recommend not checking the FG at all... If you've used the yeast before, and you see the active fermentation on schedule, then you probably have a good idea of how long it takes.

I've been using Safale-04 and 05 lately and they are speedy. I don't transfer to secondary anymore, and I don't bother checking the FG until I bottle (right from the carboy) after week 2. I mostly brew IPA's and use speedy yeast...and you said it was an IPA.

I know there are slow fermenting brews where it's really NOT clear when fermentation is complete, but in this case I have to believe that you are going to get the same FG reading, give or take. Please let us know!

 

[Aggie10]

Following advice above I tested the other halves, I actually have 2 12 L split batches going (different worts), and:
Batch 1, both FGs 1.010
Batch 2, FGs 1.012 and 1.011

Didn't want to waste beer when each split is only 12L, plus possibly taking unnecessary risks if I could get away with only sampling one split. Unfortunately, my FG data don't resolve my original question, so going forward seems safer to test each split.

 

[SRJHops]

Following advice above I tested the other halves, I actually have 2 12 L split batches going (different worts), and:
Batch 1, both FGs 1.010
Batch 2, FGs 1.012 and 1.011

Didn't want to waste beer when each split is only 12L, plus possibly taking unnecessary risks if I could get away with only sampling one split. Unfortunately, my FG data don't resolve my original question, so going forward seems safer to test each split.

Safer for sure, though from my perspective your data suggests no need to test the second carboy -- is 1.012 really that different from 1.011? Probably looks pretty close on the hydrometer I'd guess...