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Old 08-13-2012, 05:41 PM   #1
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Default Calculated O.G. Much Higher Than Actual O.G.

Hey all,

I brewed my first all-grain batch recently and things actually went smoother than I was expecting. It is an American IPA and I used a total of 17 lbs of grain. I used a couple of brewing software products i.e. Brewology101.com to get an estimate of the expected O.G. before my brew day. For this particular brew, the estimated O.G. was suppose to be 1.094. I ended up with 1.072 which seems really low for 17 lbs of grain. I am wondering since this was my first go around with sparging, perhaps I didn't sparge properly. I used the batch method with 4.5 gallons at 170 degrees. I ended up with the 6.5 gallon pre-boil volume I was targeting, so the volume of water was not an issue. Maybe the temperature was too low? Should I have done more than one sparge?

Thanks for any tips!

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Old 08-13-2012, 05:49 PM   #2
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The conversion happens during the mash. The sparge is at a higher mash just to rinse the grains.

The temperature of the mash could have been too high.

Remember MALT M=More A=Alcohol L=Lower T=Temperature

When you say OG, do you mean post or pre-boil?

What grains did you use?

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Old 08-13-2012, 06:03 PM   #3
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I used 16 lbs of 2-row and 1 lb of Honey malt. I mashed at 150 and if anything it may have been slightly under 150, like 148. The O.G. was post boil. Is there a really clear documented batch sparging procedure out there on the Internet? I followed a YouTube video that in hind sight seemed lacking in detail.

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Old 08-13-2012, 06:21 PM   #4
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Maybe the crush wasn't that good?

Also, using 70% and a theoretical average yield of 35 points per pound (assuming its not all 2 row) you end up with around 25 points per pound.
25 * 17 /5 = 85 not 1.094

If you ended up worth 72 instead of 85, thats around 60%.

When working with thicker mashes/more grain you can have lower efficiencies.
Might your mash thickness have been a little too high? Just enough to have lowered efficiency several points?

Your results are not really off that much.
Maybe stir more next time.

Quote:
Originally Posted by scruff311 View Post
Hey all,

I brewed my first all-grain batch recently and things actually went smoother than I was expecting. It is an American IPA and I used a total of 17 lbs of grain. I used a couple of brewing software products i.e. Brewology101.com to get an estimate of the expected O.G. before my brew day. For this particular brew, the estimated O.G. was suppose to be 1.094. I ended up with 1.072 which seems really low for 17 lbs of grain. I am wondering since this was my first go around with sparging, perhaps I didn't sparge properly. I used the batch method with 4.5 gallons at 170 degrees. I ended up with the 6.5 gallon pre-boil volume I was targeting, so the volume of water was not an issue. Maybe the temperature was too low? Should I have done more than one sparge?

Thanks for any tips!
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Old 08-13-2012, 08:51 PM   #5
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+1 on the crush. I just adjusted my crush a little finer and got about a 6 % increase in efficiency. All other processes were kept the same. Once you dial that efficiency number in, the software will be much more accurate with its predictions.

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Old 08-13-2012, 09:20 PM   #6
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60% really isn't that bad on a first try - especially with a higher gravity beer.

If you used 4.5 gallons of sparge and collected 6.5 total, that means you only had 2 gallons from the first runnings. For batch sparging, you want the 2 runnings to be about equal. You must have had a pretty thick mash with that much grain and that little strike water.

170 sounds a little low for the sparge water temp - what was it once you stirred it in?

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Old 08-13-2012, 09:51 PM   #7
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My strike water volume was 4.25 gallons (using the 1 quart per pound rule) and unfortunately I didn't take a temp reading once I added the sparge water. When should I be stirring the mash? I guess I was afraid to lose heat and once the strike water was in, I gave it a quick stir and sealed the HLT up for an hour.

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Old 08-13-2012, 09:56 PM   #8
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+1 on the crush, get a better crush and efficiency will improve.

You should stir about half way through the mash to mix things up IMO, work for me and you should also be stirring as you dough in to be sure you aren't getting doughballs. For sparging go to http://www.dennybrew.com Detailed instructions are there! Also make sure your sparge water is at least 170 to get a good rinse of those sugars

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Old 08-14-2012, 12:17 AM   #9
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I 2nd checking the crush, and I find I get far better efficiency if I mash around 1.5 qts/lb of grain. I personally don't notice any higher efficiency stirring throughout the mash, but each system is different. I batch sparge with 180-190f water and stir like mad before collecting the 2nd runnings. Higher gravity beers can be hard to get decent efficiency

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Old 08-14-2012, 12:24 AM   #10
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Quote:
Originally Posted by scruff311 View Post
I used 16 lbs of 2-row and 1 lb of Honey malt. I mashed at 150 and if anything it may have been slightly under 150, like 148. The O.G. was post boil. Is there a really clear documented batch sparging procedure out there on the Internet? I followed a YouTube video that in hind sight seemed lacking in detail.
Here is a good PDF from Bobby_M
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Revvy>>You shouldn't worry about ANYTHING, you didn't hurt the yeast, they know what they need to do, they want to eat all that sugar they are swimming around in. They want to pee alcohol and fart co2, it's their nature.

Bobby_M>>I flood the keg with CO2 for one minute with the lid off, rack the beer in to the bottom gently, seal it, flood it, vent it. If there's still O2 in there after that, F it.

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