I've heard that higher gravity beers will see a lower efficiency, but my understanding for the cause is a reduced amount of sparge water with a standard all grain brewing process. Since BIAB doesn't require a sparge, would this phenomenon still exist? The reason I ask, I did my third all grain BIAB yesterday, a planned 1.077 beer, and only got 64% versus my first two of 70%. Another potential factor: Could water to grain ratio also be a cause? My first was 2.5 qt/lb, 70%, 1.054, second was 3.8 qt/lb, 70%, 1.043, and third 1.5 qt/lb, 64%, 1.067, planned of 1.077. The reason my water to grain ratios differ is because of a small boil kettle limitation. I have been leaving out some water during the mash and adding it for the boil after grains are removed.
High OG=lower efficiency and BIAB
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Yes, I think you could expect a lower efficiency anytime you have a larger grain bill.
Here's why- say you're making a 5 gallon batch with 10 pounds of grain. You can easily use enough water to get to your boil volume without undersparging (or whatever it is you BIABers do!). You're using enough volume to get to your boil volume.
But say you have 25 pounds of grain. You could use 3 quarts of water per pound of grain, for maximum efficiency (mash and sparge). But you'd have like 22 gallons of wort (guessing- didn't do the math!) to boil down to 5 gallons! So most people would take the efficiency hit, and only mash/sparge up to the boil volume.
As far as mash efficiency and mash thickness is concerned, I don't have an answer. If you check your pH and you pH is in the correct range it would affect the efficiency. But in my system, if I go up over about 1.75 quarts/pound with my tap water, my pH gets too high. If I was over 2 quarts/pound, I would have a pH of over 6 without treating it. But I'm not at all experienced with BIAB and I know that you mash with the whole volume instead of the traditional mash/sparge so I really don't know what the pH would do, and how/if it would impact the efficiency.
I think the issue is more just the lower volume of water per pound of grain being used in a bigger grainbill.
Here's why- say you're making a 5 gallon batch with 10 pounds of grain. You can easily use enough water to get to your boil volume without undersparging (or whatever it is you BIABers do!). You're using enough volume to get to your boil volume.
But say you have 25 pounds of grain. You could use 3 quarts of water per pound of grain, for maximum efficiency (mash and sparge). But you'd have like 22 gallons of wort (guessing- didn't do the math!) to boil down to 5 gallons! So most people would take the efficiency hit, and only mash/sparge up to the boil volume.
As far as mash efficiency and mash thickness is concerned, I don't have an answer. If you check your pH and you pH is in the correct range it would affect the efficiency. But in my system, if I go up over about 1.75 quarts/pound with my tap water, my pH gets too high. If I was over 2 quarts/pound, I would have a pH of over 6 without treating it. But I'm not at all experienced with BIAB and I know that you mash with the whole volume instead of the traditional mash/sparge so I really don't know what the pH would do, and how/if it would impact the efficiency.
I think the issue is more just the lower volume of water per pound of grain being used in a bigger grainbill.
Yes the amount of water affected your efficiency.
If you were to add a sparge step I think that your efficiency would be over 80%. That is what I got on the two BIAB batches that I did before I moved to all grain.
If you were to add a sparge step I think that your efficiency would be over 80%. That is what I got on the two BIAB batches that I did before I moved to all grain.
I've thought about using the water I've left out of the mash to do some kind of make shift sparge, I'll probably try it next time. Previously I've just dumped it in the kettle, already boiling, so I'm at a boil in no time! I also adjusted my water this time. For the first two I used all spring water from the grocery store. This time I used half spring and half filtered tap. Next time I think I'll go back to all spring and try a sparge.
1MadScientist
Well-Known Member
I have been doing full volume BIAB.
No, not is I understand it. Your 2nd BIAB looked to be a full liquor mash. Your efficiency was lower because of the higher grain bill and BK size.
I've done 7 BIAB 5 gallon batches all with efficiencies between 79-84% with starting gravities up to 1.063. I hope to get the same efficiencies when I make my first 10 gallon batch. I don't see why not.
I unwittingly stumbled upon the BIAB process for my 3-gallon sized batches before I read it here on this website (if only I'd come here sooner...lol).
Nevertheless, I've found (like others have mentioned in other threads) that by taking the grain bag and dunking/batch sparging it in another kettle/bucket with water at 170 degrees, that efficiencies of 75% or greater are easily attainable.
FWIW, I've done numerous BIAB batches with OGs approaching 1.090 and love its simplicity.
Nevertheless, I've found (like others have mentioned in other threads) that by taking the grain bag and dunking/batch sparging it in another kettle/bucket with water at 170 degrees, that efficiencies of 75% or greater are easily attainable.
FWIW, I've done numerous BIAB batches with OGs approaching 1.090 and love its simplicity.
2nd was a full liquor mash, which was a mistake. 3.8 volume needed, 4 gal kettle (2.5 gal batch). My grain bag was wicking up wort causing it to dribble down the side of the kettle. Now I just leave out water to keep the kettle at about 3.25. Next time I'll do a sparge with the extra water instead of simply pouring it in the kettle for the boil. Might keep the mash ratio lower (2-2.5 qt/lb?) to hopefully create more sparge water.
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