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-   -   biab water to grain calculator (http://www.homebrewtalk.com/f36/biab-water-grain-calculator-346342/)

weeple2000 08-08-2012 05:12 AM

biab water to grain calculator
So from what I understand, efficiency depends on what the limiting factor is when brewing. For the best efficiency, you don't want to be limited by how much water you can biab with. My question is how do I know those limits? When is the amount of grain the limiting factor? I have a bayou classic pot which is 11 gallons.

Is there a calculator online somewhere?

captainL 08-08-2012 01:12 PM

I just work it backwards.

Finished wort 5.5 gallons
+1.5 boil off ..for 1 hour boil
+1 gallon for grain absorbtion, for about 10 lbs of grain.

So I start a full mash with 7.5 gallons of water.

If I boil longer, I adjust
If I use more grains I adjust.

ArcLight 08-08-2012 01:15 PM

Is your question - "What is the optimal water - grain ratio for mashing?"
There is a great thread here by Kaiser, its stickied.

Anywhere from 1.25 to 2.5 should be ok.
Palmer says 2.5 may cause the enzymes to denature faster, but it seems to still be very effective.

For BIAB your 11 gallon pot is fine for any 5 gallon BIAB brew.

The other question is how much volume does a pound of grain fill? Keep in mind that a 10 pound bag of grain may fill a 5 gallon pot, but when you add water it fills in the air space so you can add more water.
I think a rough rule of thumb is:

4 pounds of grain = 1 quart (its actually a bit less)

so an 8 gallon batch, using 24 pounds of grain, requires 32 quarts + 6 for the grain = 38 quarts = 9.5 gallons

You can fit it in your pot. You can even use more water since you will lose around 2.5-3 gallons of water absorbed, unless you SCOOB (squeeze the crap out of the bag).

With higher gravity beers, you may want to have a 2nd pot to sparge the bag (i.e dunk and let sit for 10 minutes at 167F) to extract more sugar.

SkipWankman 08-09-2012 10:14 PM

I am a new BIAB brewer, and don't you also have to account for sparge water as well? Can you add the sparge volume after mash? Also what is the general rule for sparge volumes?

ArcLight 08-10-2012 03:20 AM


Originally Posted by SkipWankman (Post 4318763)
I am a new BIAB brewer, and don't you also have to account for sparge water as well? Can you add the sparge volume after mash? Also what is the general rule for sparge volumes?

For BIAB, you don't necessasrily have to sparge, you put all the grain and water in your pot at once. When you raise the bag, let it drain , then maybe squeeze (or press it with something like a pitcher, and an oven rack). You probably dont want to mash with too much water (10 pounds of grain and 7+ gallons of water - 1 for the boil off, 1 for the loss to the grain). In that case you may want to add water after the mash
... or ...

I have found that if you do hold back some water (mash in less) and then after raising and squeezing the bag, and putting it in a smaller pot of hot water (to mash out at 167/8) you will get extra sugar.

I strongly suggest you read the stickied thread here on BIAB.
There is a lot of information, and if you are going to do something, you are better off learning more than less.

(I also read a bunch of articles on biabrewer.org and aussiehomebrew.com)

paraordnance 08-13-2012 09:25 PM

Here is what I do for my BIAB process. Its not true BIAB but it works for me, I brew like this for at least a year and a half and I don't see myself messing with mash tuns, water transfers etc.
Regardless of grain bill (8-16 lbs seems to be max) I always start with 6 gal of water in 10 gal kettle. I heat it up on turkey frier and mash in that amount. It gets close to the top with big grain bill and efficiency suffers, but not much. After mash I pull grains out, set oven rack on top of kettle and let grains drain in basket (perforated aluminum basket with holes that came with kettle). Then I just sparge until I hit my pre-boil mark. Usually 2-2.5 gal more. If I boil longer, I sparge more. Thats it. Very simple and no guess work about how much water you need to start with. Always 6 gal. Works every time :)

weeple2000 09-16-2012 08:29 PM

Ok, not to bump an old thread but I am in the process of my second attempt and I am wondering if I have found the limits of my pot.

Here is the recipe, I am using wet hops.

15 lbs Maris Otter
1 lb British Crystal 60L
mash at 153 for 1 hour

1.5 oz Columbus @ 60

12 oz unknown wet hops at 0


og 1.082
fg 1.021
abv 8.11
ibu 71.75 1.5 oz columbus
srm 12.1
14.51” mash water 8.99 gallons
strike 159.94
pre-boil 11.29” 6.99 gallons
post-boil 9.67” 5.99 gallons
transferred 5.50 gallons

I have the basket along with the pot in addition the the bag in there, and after I finished adding the grain to my strike water I spilled a bit onto the driveway. I suspect the extra hops might have something to do with this.

Has anyone made a bigger beer with this pot, or have I found the limits of it? I am lucky that I just barely overflowed it.

I am thinking it may have been a better idea to mash in with a couple gallons less and batch sparge the grain in my 5 gallon pot when I am done mashing.

Also, when you mash, do you leave your grain sit and slowly cool from the strike temperature? If my recipe calls for mashing for an hour (seems a bit long), the temperature will be different after the hour is done compared to when it begins. I could direct fire my kettle to get back up to 153 if need be.

wilserbrewer 09-16-2012 08:44 PM

You will fit more grain without using the basket. Also, as your gravity increases, a sparge will help more with efficiency, and also help to cure small pot issues as well. An 11 gal pot should be ample w/ 16 lbs of grain for a 5 gal. batch without the basket, I'm not sure of the volume of the basket. I have that pot and basket, and only use the basket for seafood steaming, never tried it w/ BIAB.

using the rackers calc, can i mash it here
16lbs of grain at 2.3 qt/lb is 10.5 gal roughly starting w/ 9 gal of water...so this is very close to the limits of an 11 gal kettle for a five gallon batch.

Transamguy77 09-16-2012 08:53 PM

When I was using a bag I started all my batches with 5 gallons in a 7.5 gallon pot and then sparged in my 5 gallon pot with 2-3 gallons and added that to my kettle.

As far as temp goes I used to wrap my kettle with 3-4 bath towels and only loose a few degrees, although everything I've read states the the most conversion happens in the first 20 mins and that is the most important time to hold the temp. I now use a keggle as my mash tun and I wrap it in an old comforter and only loose a few degrees.

weeple2000 09-17-2012 04:17 AM

I used the calculator to determine how much water to use, and I think it doesn't account for wet hops.

I wound up with too much at the end, I marked my carboy with tape for the 5 gallon mark, I can't remember if the bottom of the tape is 5 gallons or the top. It is a 6 gallon carboy and the tape is 12.5" from the bottom of the carboy on the bottom of the tape and 13" from the bottom of the carboy to the top of the tape.

The liquid is 15" from the bottom of the carboy. Around 14.5" the carboy starts to taper. So I am thinking that I wound up with closer to 6 gallons of beer. (14.5 / 12.5) * 5 = 5.8, (15 / 13) * 5 = 5.77 gallons.

The gravity was 1.060 at 75 degrees F post boil. I am thinking my efficiency leaves something to be desired. I did not sparge, I did not heat for mash out. I did squeeze the bag a fair amount though.

Using the efficiency calculator here:


I wind up with about 57.57% efficiency assuming I wound up with 5.7 gallons. Like I said, I didn't measure the amount at the end. I could measure it before I bottle it. Any suggestions as to how to improve?

I believe I should do a sparge, probably with 2-3 gallons in my 5 gallon pot and mash with that much less. I think the larger grain bill from this recipe calls for it more so than usual. Any other suggestions?

This brings about another point of contention, will I have issues with the fermentation assuming I have that much liquid in a 6 gallon carboy? I started 2 5 gallon batches of cider and didn't leave enough head space and they bubbled over, I'd hate to make another mess. I could always take out 3/4 of a gallon tomorrow if that's the consensus.

...edited: I just realized that assuming the .5 for trub, I should have 5.5 gallons so I haven't missed my mark by that much. Which begs the question, which numbers do I use for efficiency calculation? 5.7 or 5.2, assuming .5 lost to trub?

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