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Old 06-25-2012, 06:45 PM   #1
Jan 2012
Stewartsville, NJ
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So I've been brewing almost weekly since January. As I've come to brew more and more, I've started to hone in on my processes. Earlier, I just wanted to make beer. But now I want to follow recipes and calculate for efficiency and IBU's. I brew 1-gallon all grain batches using a 3 gallon stainless steel stock pot and a 5 gallon paint straining bag from Home Depot.

As I've progressed, I've been more and more mindful of my efficiency. I'll find a recipe I like, scale it down using the free Brewer's Friend website, and then adjust per my efficiency. However, my efficiency seems to flucuate between 70 and 66. Sometimes going up to 71, but never really lower than 66.

My process is as follows:

I use a 3 gallon stainless steel stock pot with a built in strainer for pasta. I line the pot and strainer with a paint strainer bag from Home Depot. The built in strainer allows for the bag to sit on the bottom of the pot and not burn. I calculate the amout of total water I need, erring on the side of an additional 1/2 quart or so. I use an online BIAB calculator to determine my strike water temp, inputting variables such as kettle diameter, temp of grain, amount of hops/grains, etc. Once I achieve my strike water temp, I add my grains and stir like hell until I reach my mash temp. I know that dough balls can be an issue, so I'm incredibly careful to stir everything, completely. Once my mash temp is reached (usually about a minute of stirring), I cover, wrap in about 3 towels, and put in a pre-warmed (that I turn off as soon as my mash temp is reached) oven for 60 min. After 60 min, I put the pot back on the stovetop. At this point, I'll take another temp reading and usually find that I've lost about 4 degrees on average from my starting mash temp. I then turn the heat back on and stir constantly as I bring the temp and grains up to 170. Once 170 is hit, I cut the heat, cover with the stock pot with the lid, and let it sit on the stovetop for 10 minutes to "mash out." After the 10 minutes are up, I pull out the pasta strainer and bag and squeeze the ever lovin be-jesus out of the bag as I crank the heat on the kettle, achieving my boil.

I'm right on the mark volume-wise, give or take a few cups or so. I haven't "topped off" with water since about batch number 4 or 5. Sometimes I have a little too much left over, but its usually gunky and hot break material anyway.

I'm wondering why I can't hit a consistent efficiency using this method. Sometimes it's 70%. Sometimes it 66%, and other times it's in between. There have even been times that it's over 70%, but rarely. I always ask my LHBS to crush my grains extra fine, and I always use them within 7 days of purchasing them.

The only thing I can think is that since I'm using a 3 gallon stock pot with 1.8 gallons of water (on average), I'm losing some heat through the headspace between the wort and the lid (as it's sitting in the oven wrapped in towels). Does this sound like a possibility?

I do a full volume BIAB, so as my water is heating to strike temp, it's also heating my kettle, so I can't be losing any heat through a "cool" kettle.

I don't know what else to do. I know it's not a huge issue, but I want to at least have a consistent efficiency.

Looking for some help...Thanks!
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Old 06-25-2012, 07:12 PM   #2
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NordeastBrewer77's Avatar
Apr 2011
Minneapolis, Minnesota
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I've been brewing BIAB for some time now and I've found it hard to dial in an exact eff., it varies from ~70% to ~80% give or take. Some things I've learned that help w/ eff. is first and foremost, a good crush. If you're crushing at the store, mill it twice or ask them to mill it fine for a BIAB method. I'd highly recommend getting a mill, since I got mine I've upped my eff. in general. Also, stir the mash to ensure that the wort temps aren't stratifying. I stir every ~15-20 mins when I check temps. Make sure your pH is solid, 5.2 is ideal but under 6 and you're good. I use spring water for almost all of my brews 'cause our tap water is moderately hard and alkaline, this ensures that my grains will lower the pH properly. For really light beers, I'll use 5.2 stabilizer just to be sure.
I try to keep my sacch. rest temps stable (based on recipe) for 45-90 min (again, on recipe). Fluctuating temps can hurt mash eff. It's no exact science w/ BIAB, and if you're tun isn't full you'll lose some temp for sure. I like to keep a pot of boiling water ready, and some room temp water at hand in case I over compensate for loss. Stirring in the hot or cool water to adjust temps works a lot better than heating it with the burner, IME. Sometimes I end up with a thinner mash at the end, but I haven't noticed it to affect the beer at all.
Basically, just brew a lot, you'll get it dialed in. And like I said, your eff's may vary a bit from recipe to recipe, but you should be able to keep it over 70% for the most part.
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Old 06-25-2012, 07:34 PM   #3
divrguy's Avatar
Dec 2011
, California
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+1 on what Nordeast said.

It really doesn't sound like you're doing anything wrong. I noticed my BIAB efficiency went up when I made sure I had enough or slightly higher amounts of water than the calcs said and boiled slightly longer if I had a touch too much wort. I was bummed this weekend when I brewed a rye and eff was 79% but I also re-checked and ended up not putting enough water in my mash. I also had one low eff brew in the beginning and found as Nordeast mentioned my LHBS didn't crush right. But now I ask for a double mill and eff is way up.
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Old 06-25-2012, 07:40 PM   #4
Insomniac's Avatar
Apr 2011
Oxford, UK
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The only thing I do differently is that I dont have as big a pot as you so my mash volume is a little lower, but after bringing it up to 170 at the end of the mash I then move it over to a fresh pan of water at 170 to rinse. I keep doing this until I get my pre boil volume at which point the water is pretty clear.

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Old 06-25-2012, 07:55 PM   #5
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Jul 2010
SF Peninsula
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Originally Posted by Insomniac View Post
The only thing I do differently is that I dont have as big a pot as you so my mash volume is a little lower, but after bringing it up to 170 at the end of the mash I then move it over to a fresh pan of water at 170 to rinse. I keep doing this until I get my pre boil volume at which point the water is pretty clear.
I was going to suggest this too. What's your average total grain weight - with close to 2 gal strike volume on a tiny batch like that I would guess you would be getting up in the 3.5-4.0 qt per lb range for mash thickness. Maybe it's throwing off your pH, do you measure that?

The other thing to do is just adjust up your recipe to account for your efficiency. Sounds like you've at least got a pretty reproducible range.

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Old 06-25-2012, 08:03 PM   #6
Jul 2011
Richardson, Texas
Posts: 1,025
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I've been using hybrid, squish-sparge BIAB for a while and never measured my efficiency, but I have always been able to use common recipes with no adjustments.

I just switched to full-volume, mashout, no-sparge BIAB because I got a keggle that is large enough. Per Hopville my efficiency was 66%.

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Old 06-25-2012, 11:28 PM   #7
Sep 2010
upstate of SC
Posts: 299
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You are on track. My BIAB eff is usually between 75-80%. I stir every 20 minutes and light my burner if it is needed to get back to mash temp. The other thing I would add is to squeeze the bag to get all the extra sweet juice out. This will help increase efficiency.

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Old 06-25-2012, 11:30 PM   #8
Nov 2011
denver, co
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You might try adding a mash out step to your mash schedule.

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Old 06-26-2012, 01:21 AM   #9
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ajf's Avatar
Oct 2005
Long Island
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You get efficiencies between 66 and 70%. So your efficiency is 68% plus or minus 2% That's pretty good consistency for a 1 gallon batch.
You say
" I calculate the amout of total water I need, erring on the side of an additional 1/2 quart or so."
That additional 1/2 quart in a 1 gallon batch could change your efficiency by 12.5%
You say
"I'm right on the mark volume-wise, give or take a few cups or so."
That few cups or so is probably caused by adding a little bit of extra water. If you made 5 gallon batches instead of 1, then your efficiency variations would be reduced by a factor of 5 (assuming your volume variations remain the same).

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