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BIAB Crazy Low Efficiency

Hey guys,

Ive got quite the conundrum here. I did my first BIAB on Saturday,
and ended up with a pre-boil gravity of 1.020 on a 13 pound grain bill. I
will post the recipe and describe my technique below.

Recipe Type: All Grain

Yeast: WLP001

Yeast Starter: Absolutely

Batch Size (Gallons): 5

Original Gravity: 1.070

Final Gravity: 1.018

IBU: 67.4

Boiling Time (Minutes): 60

Color: 4.8

13 Pounds 2-row (US)
6 ounces Thomas Fawcett amber malt.

I put 5.6 gallons of store bought water into my kettle and heated it
up to the strike temperature. After it was reached, I slowly mixed in
all the grain, and nailed my mash temp of 152. Roped a blanket around
the kettle and let it sit, about every 20 minutes I stirred and measured
the temperature with my kettle thermometer, as well as a hand held
thermometer, I had to slightly heat the mash about halfway through (60
minute mash) but it still maintained 150-152, so im 99% sure temperature
was not a factor here.

Afterwards, I pulled the bag and let it drain on a stove grate above
the kettle. I squeezed it a bit, but did not “strangle” it, so to say. I
then heated my 2 gallons of sparge water to 170, and slowly poured it
over the grains for about 15 mins.

I took a sample of the wort, and stuck it in the freezer. Once it
reached my hydrometers calibration temp using my thermometer, I checked
the gravity with 2 separate hydrometers, both were 1.020.

HOW DID THIS HAPPEN?? I feel like I followed everything to a T. I
nailed my pre boil water amount, and ended up right at 5 gallons at the
end of the boil. I specifically requested my LHBS to double mill the
grains for me.

Im at a loss here and not really sure how to move forward to increase
my efficiency drastically with my next batch, if anyone can offer some helpful advice it
would be most greatly appreciated.

EDIT: I added roughly a half pound of DME during the boil, and my post boil gravity was 1.068.


What was the post boil SG?

It was 1.068 after dumping in about 1/2 pound of DME, maybe a bit more.

Edit: Something isn’t adding up…you would’ve needed several pounds of DME to get that many gravity points.

Edit #2: Removed comments about pH…

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Quick dumb question…was your grain crushed?

I was going to ask that as well, but they mentioned requesting double crushed grains…

Your wort was probably stratified, and you grabbed a sample of the lower gravity wort floating on the top of your kettle. It happens… But yeah, there’s no way you could have boiled 1.020 wort to 1.068 by just adding half a pound of DME. Give it a good stir next time before you grab a hydro sample.


Its coming down to this, or the grain’s were not crushed as well as I asked for.

I was thinking the same thing. 1 lb of DME in 5 gallons would get you about .030 from .020. 1/2 would only get you around .025 from .020. Something’s wrong

Even a bad crush you should have done better with that much grain

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Yup, all fingers are pointing to stratification. Even without the DME, the calculations show it should of been roughly around 1.060. Thanks everyone for the info! It helped alot, next brew day ill make sure to stir the wort after the sparge.

I do this every time if i sparge.

Stir it. I literally just did that experiment this past Saturday just to see what would happen. I took a sample of wort as it first came out of my mash tun and into my boil pot. After 45 minutes of sparging I took another sample which was clearly lighter in color. The first gravity was 1.065 and the second reading was 1.030.

For point of reference. I had a bad crush recently. I didn’t notice until too late that my mill roller slipped.
There were lots of completely intact kernels floating in the mash. I just went with it, and made no sugar or DME additions.

BeerSmith predicted I’d have 1.066 assuming 75% efficiency. Post-boil I ended up with 1.057.

My high-gravity Irish red turned into a normal Irish red. It was pretty tasty though. The keg just kicked last week.

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