84% efficiency? What am I doing wrong?

[BlackJaqueJanaviac]

I'm such a newb that I have trouble believing that I got 84% efficiency in my last batch. I must not be measuring something correctly or my calculations are erroneous.

O.G. measured after cooling wort to 74F was 1.052. I filled a 6 gallon primary bucket to within 1 inch of top, filled a 1 qt decanter for my yeast ranch, and dumped the rest (maybe a 1/2 gallon of sluge) on the lawn.

I used 9 lbs of Pale Ale + 1lb Crystal 60L.

I measure gravity with the little plastic tube the hydrometer comes in and I noticed it "sticks" to the side. Some readings were 1.056 down to 1.052 and everything in between.

I figure:

9 lbs Pale Ale + 1lb Crystal 60L (37x9/6 = 55.5 + 34*1/6=5.6) should have a max gravity of 62. So 52/62 = 84%.

What has me puzzled is that as I read it seems like some guys go through contortions to get 84% efficiency. I guess I can't believe I'm that lucky since my process is so simple.

I fill a 21 qt boiler to almost full, heat it to 180F. Dump it in a 48 qt cooler, leave uncovered 'til the temp is down to 170F. Add grain bill (crushed in my Victoria mill). Add a little more cold water to get 153F. Let sit for 1 hr stirring every 15 min. Lauter into a 48 oz pitcher then into 33 qt boiler. Add another 21 qt pot of 150F water let sit for 15 min, then lauter and drain into boiler.

 

[malkore]

Is your hydrometer calibrated to 74F? Most are calibrated at 60F.

 

[bob1852]

How are you measuring volume? Volume accuracy is extremely important in efficiency calculations as at 6 gallons your max is 62, but at 5 it's 73.5 (or the difference between 84% and 71% efficiency)

And, 1.052 @ 74*F is closer to 1.054 @ 60*F.

 

[jerryalan]

I filled a 6 gallon primary bucket to within 1 inch of top, filled a 1 qt decanter for my yeast ranch, and dumped the rest (maybe a 1/2 gallon of sluge) on the lawn.

It doesn't sound like you have an accurate measurement of your wort volume.

 

[TripHops]

Yeah, the previous posts regarding volume are correct. There are also two other factors that might be skewing your calculations. 1) Your SG needs to be measured at 60deg. At 74deg it is not giving you the correct reading, 2) you need to measure your SG at the end of the boil, not the beginning.

I use this SG on-line calculator to get a more accurate reading at 60deg regardless of the temperature of my wart.

http://dd26943.com/davesdreaded/tools/convert.htm

Try that next time and I think you will get close to your real efficiency percentage.

Good Luck,

Trip

 

[bannonb]

can you get a consistent reading on water with your hydrometer? it should be 0. Every hydrometer I've used is off by 2-4 points...meaning water is .996, so I always have to add .004 for accuracy when sugar is involved.

Temp may be an issue certainly also.

I batch sparge and my rig consistently hits 73% efficiency. Some fly spargers say they are up near the 80s so you may be one of the lucky ones.

 

[BlackJaqueJanaviac]

Thanks guys.

Most of what was suggested would actually increase my efficiency. In other words if 1.052 @ 74F would translate to 1.054 @ 60F then plugging in 54 into the equation would yield 87%.

However accurate measure of wort volume might be key. How does one get a good measure on wort volume?

I made a foray into trying to calibrate my 6 gallon bucket, but I gave up. I started out using a 1 pint measuring cup to fill a milk jug with 8 pints and mark it. Then I was going to fill the bucket one milk jug at a time, marking the water level after each jug-full. But I found that a 1 gallon milk jug did not hold 8 pints of water! So either my measuring cup was off, my method for filling the cup introduced too much error, or the milk jug was less than 1-gallon.

 

[Rahahb]

I double batch sparged my first ag and got 85% efficiency. I feel confident of my findings. So maybe yours is correct too.

 

[broadbill]

Did you take a pre-boil gravity reading?

 

[BlackJaqueJanaviac]

No, I did not take a pre-boil gravity reading.

 

[broadbill]

No, I did not take a pre-boil gravity reading.

The reason I ask is that you can you can figure out if one of your volume readings is off based on what you got for a pre-boil gravity versus post-boil. The only thing that should happen between the two is evaporation.

You have the same amount of gravity points (total) pre-boil as you do post-boil (barring accidents like boil over, or other losses). If you don't, then something is up...

 

[TripHops]

I double batch sparge as well and have been able to get approximately 79% efficiency, which is close enough for me. I simply add a little more grain to the bill to get the SG exactly where I want it to be.

Trip

 

[bob1852]

However accurate measure of wort volume might be key. How does one get a good measure on wort volume?

I made a foray into trying to calibrate my 6 gallon bucket, but I gave up. I started out using a 1 pint measuring cup to fill a milk jug with 8 pints and mark it. Then I was going to fill the bucket one milk jug at a time, marking the water level after each jug-full. But I found that a 1 gallon milk jug did not hold 8 pints of water! So either my measuring cup was off, my method for filling the cup introduced too much error, or the milk jug was less than 1-gallon.

Without accurate volume measurements, efficiency cannot be reliably calculated.

You also need to take into account how temperature affects volume.