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Bad Efficiency

mbg

Master Brewer
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I've been brewing all grain for quite a few years now (5-gal. Batches). I usually buy grain and mill it myself. I used a 48 Qt. Ice Cube cooler and consistently got mid to low 70's for eff.. I recently bought a few unmilled all grain kits when they were on sale at NB. I also built a new mash tun from a 70 Qt Xtreme rectangular cooler. I hit the mash volumes and temperatures but only had 57% eff. or close to 10 points off on pre-boil gravity.

Should I have gotten lower eff. from the new tun? Only other thing that I can think of is the grain bill could have been short?

I hope to brew again this weekend and already weighed the grain so I'll get another shot to check my eff..


Thanks,

Mike
 
Seems most likely that grain weight is at the root of your problem. Or the grain could have been poor quality.

I have a house beer I make at least every month. Once, I had to use a different base Pilsner for it and my efficiency plummeted. It turns out, that the yield for that malt batch was only 54% (instead of the typical 80 to 82%). Efficiency is based on how much of that yield a brewer get. Malt batches are huge and last months in the distribution system.

Mash efficiency is made up of many interrelated variables. Mash pH is one that you can check and control. Although water is the very last thing for brewers to think about, knowing your RA (residual Alkalinity) will help you understand the styles your water will naturally want to make.

Mash tun design and how you sparge are going to be other factors. When you grain out, do you notice pockets of sweet malt? If your new tun is taller than wide, there could be ways for water to channel through the grain bed.

Do you check the gravity of your first runnings? They should be at least 1.080 up to 1.092 for most liquor to grist ratios. Thicker mashes improve efficiency. My method is to mash at about 1 qt/lb. Then, just before recirculating, I underlet water to get to 1.25 qt/lb or maybe a little thinner if a lot of flaked grain or wheat is involved. I get consistently high efficiency and fermentability that way.

 
brewfun said:
My method is to mash at about 1 qt/lb. Then, just before recirculating, I underlet water to get to 1.25 qt/lb or maybe a little thinner if a lot of flaked grain or wheat is involved. I get consistently high efficiency and fermentability that way.

Brewfun - thanks for the reply. Can you explain what underlet means.


Also, I have a Barley Crusher mill. When I got it I set the gap at 0.035". Just for grins I checked it and found it at 0.043"! Is this enough to mess with my efficiency? (No more loaning out my mortorized mill)

What is the thinking on mill gap these days? I have seen some set it in the low 0.030's.


Thanks,

Mike
 
Underletting is adding water to the mash through the mash outlet valve. It floats the grain bed and makes it easier to mix. But don't do it if you have an unsecured false bottom.

I haven't measured a mill gap in eons. I simply grab a bit of malt and look at it. If it isn't correct, I tighten up the gap. If too powdery, I loosen it a smidge. These are tiny movements.

But, since you brought that up... When ordering pre milled malt or kits, be aware that 90% of a LHBS grain goes into extract kits. The LHBS often has the mill gap set a bit fat to avoid too much malt powder in the steeping grains. Roasted malts tend to shatter, rather than crush. It's just a pragmatic thing because beginning brewers want good results while they learn. Starch hazy or astringent beer is not good for business. So, if you think there's a few too many uncracked grains, ask them to mill it twice. That usually does the trick.
 
brewfun said:
Underletting is adding water to the mash through the mash outlet valve. It floats the grain bed and makes it easier to mix. But don't do it if you have an unsecured false bottom.

I haven't measured a mill gap in eons. I simply grab a bit of malt and look at it. If it isn't correct, I tighten up the gap. If too powdery, I loosen it a smidge. These are tiny movements.

But, since you brought that up... When ordering pre milled malt or kits, be aware that 90% of a LHBS grain goes into extract kits. The LHBS often has the mill gap set a bit fat to avoid too much malt powder in the steeping grains. Roasted malts tend to shatter, rather than crush. It's just a pragmatic thing because beginning brewers want good results while they learn. Starch hazy or astringent beer is not good for business. So, if you think there's a few too many uncracked grains, ask them to mill it twice. That usually does the trick.

Thanks for the info - never heard of underletting.

(I just noticed I posted this in the general and not all grain section. I re-adjusted my mill gap and will post results there.)


Mike
 
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