BIAB low efficiency help

[thehopthief]

I've been doing BIAB for my last 4 all grain batches and have noticed really low mash and brew house efficiency especially on two of the batches. I keep reading BIAB should net you 75-80% but I get low 60s and then this last time my pre boil gravity only went up a few points which is really bizarre cause I boiled off a bunch of water of course.

My method is use BIABcalculator.com to get total mash volume. Put all that in my brew pot. Heat water to around 100, then add my mineral and acid additions. Heat to strike temp, dough in, typically mash temp is pretty close to accurate based off calculator strike temp but can be 1-1.5 degrees high sometimes. Mash for 60 min, stirring every 15 with heat off but lid on. Finally temp usually is 145-148 or so. Then I pick the bag up and hang over wort for a bit before moving it to a bucket to let it drip until it's done. I don't squeeze at all or sparge which are two things I may try. From there it's the usual brew process.

Any advice? Anything I'm doing noticeably wrong?

 

[VikeMan]

What does your crush look like?

 

[grampamark]

Low or inconsistent gravity is, usually, attributable to a coarse crush and/or inaccurate measurements.

The OP’s basic process sounds OK. If the grain is being milled by someone else (LHBS or online retailer) it’s almost certain that it’s not fine enough for BIAB.

Water volumes should be measured, not eyeballed. Lab accuracy isn’t necessary but, at the homebrew scale, half a cup either way is a significant percentage. Using a measuring stick or stainless steel ruler will get the necessary accuracy consistently. Also, when pulling gravity samples, try to stir the wort enough to ensure a homogenous sample. Taking care to do the most basic parts of the process as accurately as possible goes a long way towards achieving a simple, repeatable process.

The difference between brewing and brewing consistently is more about the details than anything else. Chasing efficiency isn’t as important as developing a process whch will produce good beer consistently. One can make great tasting beer at 65% efficiency and mediocre beer at 85%. A consistent process will produce a consistent efficiency but that doesn’t necessarily mean the highest possible efficiency. What really matters is how good the finished product is. There’s a balance between the art and the science of brewing. Therein lies the basis for endless message board debates.

 

[McKnuckle]

In addition to grain crush, how long are you mashing since your temps drop into the 140's at the end? I would extend to 75-90 minutes unless you're mashing in the high 150's, where an hour suffices.

 

[thehopthief]

Interesting. I've never really looked into the grain crush because I just buy them from a local brew store and whatever their "default" milling is. Should i ask them to run it through twice? I thought I recall really fine grain being an issue but maybe I'm wrong.

Thanks I definitely think consistency is what I'm going for more than efficiency and that's what's frustrating. I brewed basically the same beer with the exact same grain bill twice and the first time I was spot on my calculated OG. Second time 7-8 pts low.

I typically mash for 60 min. Depending on style of course my mash temp changes but always done 60 min and water calculation based off biabcalculator.com. For example my last beer was mash in at 153. Should I be mashing longer?

 

[Squirrels]

I do a bit finer of a crush and do 70 minute mashes with a recirculating BIAB. I typically get 80-90%.

I'd try a finer crush and a longer mash. Squeezing also gets some additional efficiency.

 

[McKnuckle]

Fine crush and longer mash for sure. That'll get you most of the way there, usually into the zone where it's good enough without the additional (minor) hassles of squeezing the bag or sparging. When I do BIAB, I mill fine, do not sparge, and employ a gravity drain. I get in the 70-75% mash efficiency range.

As you say, and I agree; consistency is more important.

 

[VikeMan]

Interesting. I've never really looked into the grain crush because I just buy them from a local brew store and whatever their "default" milling is.

LHBS crushes usually suck. My guess is they want customers to have low efficiency, to buy more grain. Or they want to be very sure there won't be a stuck lauter. Either way, they usually are too coarse.

Should i ask them to run it through twice?

Definitely ask. Some will do it. Some won't. Ideally, get a mill and crush your own.

I thought I recall really fine grain being an issue but maybe I'm wrong.

From a stuck lauter perspective, "too fine" is not as big a problem with BIAB as it is with a more traditional mash/lauter process.

 

[TechFanMD]

Agreed, if you use the crusher at the LHBS or buy pre-crushed...it's too coarse. Think about investing in a mill, it really is nice to be able to control your crush.

I also added a step which is basically a batch sparge. I do the BIABcalculator as it states, then drain after the mash, then I add 3/4-1 gallon of hot water, stir, and let it sit about 10 minutes while the runnings I already collected are heating up for the boil. I then collect this and add it to the boil pot. I do have to account for the need to boil off a bit more but with my pot and burner, I have a very high boil-off rate even with a moderate boil.....I am usually glad to have had the extra liquid. I have not fully dialied this in yet but often need to add (cool sterilized) water to the fermenter to bring the OG down to near target level because efficiency is higher than planned......Once I dial it in, I'll adjust grainbills accordingly.

I brew enough to have figured this out by now but have been too lazy to care to figure it out.

 

[RM-MN]

Thanks I definitely think consistency is what I'm going for more than efficiency and that's what's frustrating. I brewed basically the same beer with the exact same grain bill twice and the first time I was spot on my calculated OG. Second time 7-8 pts low.

He who controls the milling of the grain controls the efficiency of your mash.

Interesting. I've never really looked into the grain crush because I just buy them from a local brew store and whatever their "default" milling is. Should i ask them to run it through twice? I thought I recall really fine grain being an issue but maybe I'm wrong.

If you want good efficiency and consistency, you need your own mill. It doesn't need to be expensive, a cheap Corona style will do just fine and set you back less than $30. I use one for my BIAB and would normally expect about 80% brewhouse no-sparge. However, I sparge to get to volume and now expect efficiency in the low 90's. If the mill at your LHBS is set to coarse, running through twice will help but not enough. Having your own mill also lets you buy in bulk and brew whenever you want. The difference in the cost of the grain will pay for the mill in short order.

I typically mash for 60 min. Depending on style of course my mash temp changes but always done 60 min and water calculation based off biabcalculator.com. For example my last beer was mash in at 153. Should I be mashing longer?

You need to mash until you get full conversion. With your LHBS crush that may be longer than 60 minutes as evidenced by your low efficiency. You can try a 90 to 120 minute mash to see if that helps the efficiency or you can simply get your own mill and then mash until you get full conversion. You may have to extend the mash a bit because flavor extraction takes longer than conversion. I now usually only mash for 30 minute.

 

[TyYoda]

I second the posts around getting your own mill. I set my rollers to a credit card thickness and typically get 85% efficiency with squeezing the bag. I also typically don't stir the mash or if I do, stir it at 30 minutes.

Question, do you insulate your pot during mash? You could be losing some efficiency if you aren't controlling your mash temperatures within your desired ranges. Mash PH can also impact conversion.

If you.over shoot your water pre-mash temp, use some cold water to bring it back into range before adding the crushed grain. You can remove the extra water after reaching the premash temp tonget the correct preboil volume.