OG lower than expected

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slackerlack

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What would cause my OG to be much lower than anticipated? It should have been at 1.084, but it ended up being 1.064. Im not sure what went wrong. This is my second all grain brew. The first one came out on target.
 
What would cause my OG to be much lower than anticipated? It should have been at 1.084, but it ended up being 1.064. Im not sure what went wrong. This is my second all grain brew. The first one came out on target.

It could be the grain crush, the amount of sparge water, inadequate starch conversion, and so on. Can you give some more details, like how the OG should have been at 1.084 (is that for your system? or someone else's? Whats the efficiency of your system, etc?), and your grainbill and volumes?
 
The OG should have been 1.083 going by Hopville.com, and 1.092 going by Beersmith. Looking online, I guess my efficiency is about 58%. But I am not sure if that is accurate. My pre boil OG was 1.055, but it had been sitting a while and whatever was in their with the hydrometer had settled to the bottom. Should the OG change much pre and post boil? Does it go up or down? And what causes it to change?

14 lbs American Pale Malt 2 Row
1 lb Torrified Wheat
1 lb American Crystal 40L
0.5 lb Dingemans Cara Pils
0.5 lb American Munich 10L

Batch sparge
Mash in 154 degrees 5.5 gallons
Mash out 154 degrees 3 gallons

Pre boil 6.5 gallons
Post boil 5.8 gallons
 
If you have beersmith you can adjust the efficiency to match your system. My guess is that it is set quite a bit higher than what your actual system is giving you (58%). Try entering all the ingredients and then adjust the efficiency to 58% and see if the beersmith OG is any closer to what you actually came up with. It may take a few AG batches to get your efficiency dialed in.

To your other question, pre and post boil gravity will vary quite a bit depending on how much you boil off during the boil. The gravity will increase as you boil since you are loosing water and condensing your wort.
 
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