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BIAB batch sparge grain absorption

Javaslinger

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Curious what people set their grain absorption to when doing BIAB with a batch sparge?

BIAB Default 0.586 fl oz/oz
Mash Tun Default 0.960 fl oz/oz

So if using a mash profile such as Single Infusion, Batch Sparge while doing BIAB, should I set it to 0.586 or somewhere in the middle.  I know I can back calculate from a brew day, but I'm trying to get a ball park to begin with from everyone else.

Thanks!
 

Oginme

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I measure my grain absorption for every batch (along with boil off rate) and track it.  I've set my grain absorption to my BIAB value in the standard options, since I do mostly BIAB brewing. 
 

tdev

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I see the default is .586 Oz/oz but when i measure mine it is around .27-.33 - this is far from the .586 - what are other people seeing?  Thanks
 

GigaFemto

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I do 5 gallon BIAB batches with grain weights of 11-13 lbs and I get very close to the default of 0.586. My volumes are so close I have seen no reason to change from the default. I do squeeze the heck out of my bag to get all the goodness out. If you don't squeeze I can see you getting higher absorption, but it is hard for me to see someone getting half.

I suddenly had a thought that the grain absorption may be affected by the grain crush. I have a mill gap of 0.025", and I double crush. It might be that a coarser grain crush would result in lower water absorption if the water doesn't penetrate all the way through the larger pieces in the same proportion as smaller pieces.

--GF
 
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