# 92% efficiency? Too good to be true?

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#### Hagen

##### Well-Known Member
Did my 2nd PM beer today, an APA

Here's the grain bill for the partial mash:
5 lb. American 2-row 37ppg
8 oz. German Vienna 37ppg
8 oz. Dextrine malt (Cara-Pils) 33ppg
8 oz. British Munich 37ppg

Strike water at 165*F gave me a 153*F mash. mashed for 45 min, stirring every 15 min.

I did a slow fly sparge and collected 5 gal of runnings, at that point, the gravity of the runnings were at 1.010. Gravity of the total runnings 1.044 (all corrected for temp)

This is where I want to check my math...
Theoretical gravity (5x37)+(.5x37)+(.5x33)+(.5x37)= 238.5 /5= 47.7
My yield= 44
Efficiency= 44/47.7= .922 or 92%

My mash tun is a 3gal rubbermaid round cooler with a home made false bottom.

I ran these numbers 3 times and got the same result. An efficiency like this seems too good to be true. Maybe the slow, high volume sparge has something to do with it, or are my numbers off somewhere?

Of course, the true test is if I can repeat this feat. I'm going to have to do at least 3 more batches before I can start to see a valid statistical sample.

#### Gruntled

##### Member
Looks like 92% to me if you collected 5g without adding any extract.
Congrats.

OP

#### Hagen

##### Well-Known Member
Gruntled said:
Looks like 92% to me if you collected 5g without adding any extract.
Congrats.
Added DME in the boil after topping off to 6.5 gallons. I took the above mentioned readings before that. The only problem is (if you call it a problem), I fugured the recipie on 70% efficiency, so my ABV is going to be around 7% instead of the 6% I was counting on.

#### Gruntled

##### Member
Hagen said:
Added DME in the boil after topping off to 6.5 gallons. I took the above mentioned readings before that. The only problem is (if you call it a problem), I fugured the recipie on 70% efficiency, so my ABV is going to be around 7% instead of the 6% I was counting on.
What a terrible dilemma.

#### TexLaw

##### Here's Lookin' Atcha!
Is it too good to be true? Well, yes and no. Your numbers look good, so it looks like you got that efficiency. However, you have to ask yourself what else you got. For example, did your high volume sparge lead to tannin extraction?

I am not trying to rain on your parade, now. Your beer might be great. I just want to let you know why super-high efficiencies are not always desired.

TL

OP

#### Hagen

##### Well-Known Member
I'm semi worried about extracting tannins, but I'll cross that bridge when it's ready to drink. Once I get past what would be an ideal sparge volume, in this case 3 1/2 to 4 gals, I check gravity every 2 qts. Once I get down to 1.015-1.010 I consider it done. If any tannins were extracted, it will hopefully be marginal.