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Brewing Topics => Brew In A Bag (BIAB) => Topic started by: K_Squared on April 17, 2014, 11:34:55 PM

Title: Where do you account for water loss to grain?
Post by: K_Squared on April 17, 2014, 11:34:55 PM

Hi,
I'm a BIAB brewer and trying to fine-tune my system with BeerSmith. Where do I specify the loss of water due to grain absorption? I lost .1 gallons per pound tonight. I don't see a way in the equipment or mash profile for me to specify this.
Thanks for any thoughts,
K^2

OK, Update....in the "Preferences" and then "Advanced" tab is BIAB Grain Absorb, which is listed as .586 fl oz/oz, but this doesn't really make sense to me - fl oz/ox? How does this relate to a loss of .1 gallons per pound of grain?

Title: Re: Where do you account for water loss to grain?
Post by: tom_hampton on April 18, 2014, 05:58:14 AM

There are 16 ounces in a pound. And there are 128 ounces in a gallon.

16 * 0.586 / 128 = 0.073 gallons / pound.

Title: Re: Where do you account for water loss to grain?
Post by: brewfun on April 18, 2014, 02:55:12 PM

+1 to Tom's formula. This is the way to calculate the water needed for grain absorption.

Quote from: K_Squared on April 17, 2014, 11:34:55 PM

I lost .1 gallons per pound tonight.
...
this doesn't really make sense to me - fl oz/oz? How does this relate to a loss of .1 gallons per pound of grain?

To rework the calculation to your observation:

128 x 0.1 / 16 = 0.8 fl oz/oz

Title: Re: Where do you account for water loss to grain?
Post by: OldBrewer on December 13, 2014, 05:59:47 PM

I did not like the answer BS gave me for grain absorption .88 gallons for 13lb of grain. It should be 1.3 to 1.62 gallons for the 13lbs of grain. This knocks of your total water needed? Are they assuming your going to squeeze the crap out the bag? I changed it to 1. and got a answer of 1.5 gallons loss to grain absorption. I can always boil off the extra.

Title: Re: Where do you account for water loss to grain?
Post by: grathan on December 14, 2014, 06:10:30 AM

I changed mine to 1.3 as well and have had much better success with volumes since.

Title: Re: Where do you account for water loss to grain?
Post by: brewfun on December 14, 2014, 09:50:04 AM

Quote from: OldBrewer on December 13, 2014, 05:59:47 PM

It should be 1.3 to 1.62 gallons for the 13lbs of grain. Are they assuming your going to squeeze the crap out the bag? I changed it to 1. and got a answer of 1.5 gallons loss to grain absorption. I can always boil off the extra.

The absorption loss number doesn't have to be an absolute. It can reflect your brewing technique. Changing it is available in Options > Advanced.

The most basic calculation is based on running out all excess water from the grain. So, yes, "squeeze the crap out of the bag" is one method. Then, there are brewers that leave the bag hanging over the kettle until it stops dripping. Both of those methods will yield more wort (water) than say, just waiting 3 minutes until the flow slows to a trickle.

The default number is based on average brewer reports about their absorption. The main thing is that the number is easily set to whatever you need it to be.

Title: Re: Where do you account for water loss to grain?
Post by: OldBrewer on December 15, 2014, 04:57:30 PM

Thanks Brewfun, point well noted