BIAB Low Efficiency

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amartinez

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Today I brewed my 8th BIAB batch and with each one I've been suffering from low efficiency. Today's recipe was a Belgian Quad from AHS, which was a 15.5# grain bill. My volumes were fine according to BeerSmith, but my preboil gravity was 1.066 instead of 1.081, and my OG was 1.082 instead of 1.098. After an hour mash I did an iodine test and there was a good amount of purple, I mashed for another 40 minutes and the iodine test came out clear. I'm mashing in a 10 gallon kettle and I used 8 gallons of water, and the pH was at 5.3. Every AG recipe I've done has had around 60% efficiency and I can't figure out how to improve it.

Any ideas?
 
Are you sparging? I assume this is an all grain kit designed to be used in a system with a MLT. If i'm not mistaken BIAB is known to be less efficient so the difference in methods may account for the low gravity. If its happening everytime you're consistent so you can account for that and make up some gravity with extract.
 
Finer crush for BIAB should get you similar results in efficiency to a batch sparge assuming you squeeze the wort out of the bag and have done a fine crush. For me however, 15.5lbs in a 10 gallon pot with 8 gallons of water would be pushing my limits as far as getting a good stir going to make sure everything gets wet.
 
Everything I've read about BIAB says they get higher than usual efficiency, that's why my problem is concerning me.

I was assuming the crush could be the issue, I've requested a fine crush on all of my kits, but the next thing I do will be to buy a mill. However, for the moment SWMBO is against it.
 
Support your local brew supply store if you have one and don't leave the store until the grain is fine enough for you.

I've not heard of better BIAB efficiencies, just that they can be similar to the other methods when done right. My last batch I double crushed the grains and picked up 4-5% from that, it was more of an experiment and I wound up overshooting the OG by a few points.
 
The crush could be the problem. But if you want to outline your process i'm sure others here may be able to help.
 
I've done 4 batches BIAB and noticed a ~10% drop in efficiency when I brewed with grain I thought looked under-crushed. I agree that the most likely reason is a poor crush AND to not leave the LHBS until you are happy with crush size.. With BIAB a finer crush is acceptable because there is no concern for a stuck sparge. A larger fraction of flour is OK.
 
All my brews are BIAB, and I agree that a finer crush will give you the biggest boost. However, there are many things you can do in your process that will help you as well. Here are some that have helped me:
- crushing my own grain. Finer crush will help, and more flour is acceptable provided your bag has small enough holes. And even still, you may lose more beer to trub, but I've found this to be acceptable.
- Made my own bag. Went to the fabric store, purchased some voile (think sheer curtains), and sewed it into a bag. Chances are you can find a local seamstress to do this for you. The material is fantastic, although it takes a long time to drain the wort out.
- Squeeze the grain bag thoroughly
- Batch sparge: after squeezing the grain bag, soak it for 15 min in a small volume of mash-out temp water, repeat squeezing and combine the two runnings until you reach target volume.
- Stir, stir, and stir some more! I find that I have to stir every 10 minutes are less. If I wait longer, efficiency drops rapidly
 
Everything I've read about BIAB says they get higher than usual efficiency, that's why my problem is concerning me.

I was assuming the crush could be the issue, I've requested a fine crush on all of my kits, but the next thing I do will be to buy a mill. However, for the moment SWMBO is against it.

Perhaps if you did as I did and bought a cheap Corona knock-off instead of the Barley Crusher so you were only spending ~$30 your SWMBO would agree. Sometimes the budget gets pretty tight but I can usually squeeze a little out of it.

Tall capacty Cast Iron Corn Nuts Grain Mill grinder NEW | eBay
 
Large beers w/ such high gravities will be less efficient, perhaps even more so using BIAB.

This has certainly been my experience in BIAB.
1050 I can get 80+%, 1070 it drops to about 65%.

Most kits seem to be formulated for 70% efficiency with a typical batch/fly sparge setup.

For BIAB I'd say either squeeze the bag like it owes you money + dunk sparge in clear water, or have some DME on hand to get those high gravities.
 
- Stir, stir, and stir some more! I find that I have to stir every 10 minutes are less. If I wait longer, efficiency drops rapidly

this^ is a great point. the temps really stratify in the BIAB mash, uneven temps can lead to poor conversion in the mash, stirring equalizes the temps.
my last brew i got ~80% efficiency in a 70 minute rest doing BIAB, gently stirred the mash every 10-15 mins.
making sure your grains are finely crushed is another good idea to boost efficiency, but i think making sure you don't have hot and cold spots in your mash is the best way to correct poor efficiency when doing BIAB.
 
I hate to bump a zombie thread, but at least it's one that I created. Sorry for the late response, but I haven't had much free time to devote to brewing :(

Anyway, regarding my process: I usually mash out for 10 minutes and then dunk the bag in mash liquid a few times before moving it to a bucket and pouring a gallon of 175° water over it. As I bring the water up to a boil I let the bag continue to drain and add the contents every few minutes.

As was stated in the thread, I plan on getting a grain mill and stirring the mash more to equalize temperature. Thanks for all the input so far :)
 
Do a google search for corona mill. I found a circus food supply site (think hot dog carts, cotton candy machines, ect...) that sold them for $17. Shipped it was $26. It will pay for itself in no time.
 
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