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Old 12-02-2012, 05:58 PM   #1
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Default Frustrated: Always (Well) Below Gravity Targets

So I've been doing all-grain for awhile now, and I have 7 AG brews under my belt. Every single one of them has been drastically under the target gravity.

Example: last night, it was a brown ale. I mashed 6.25 lb 2 row, and about .4 lb each of 40L caramel, carafoam, and chocolate malt in 3 gallons of water at 150ish, pH=5.1, then batch sparged with another 3 gallons of 170F water (with a good stir and a 10 minute rest). Target pre-boil OG was 1.043 (assuming only a 68% efficiency), target post-boil 1.052. The first run mash gravity was 1.057, but once I added the sparge wort to the first run, it was only 1.030 (which, mathematically, means the sparge water was basically just plain water). I had to add almost a pound of DME to get the gravity up for my puny 3.5-4 gallon batch. That's about 60% efficiency.

Another example: my last hefe. Target pre-boil was 1.046, target post-boil was 1.052. First run gravity was 1.070 (3.3 gal mash water), but after 4.7 gal of sparge water, the gravity was 1.032. That's 56% efficiency.

And that seems to be the pattern with all of the brews, they all come in drastically under. I've checked the temperature, the crush is good I think, I've used all different sorts of water, I have a cooler with a false bottom and don't get stuck sparges.

I should mention, my goal is time savings and predictability, so buying extra grain to make up for my lousy efficiency isn't a big deal, even going no-sparge would be fine. But, I feel like there's something wrong with my process that's causing this to be happening, and I'd love to correct it.

Any ideas?



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Old 12-02-2012, 06:03 PM   #2
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It sounds like your process is sound. I would lean towards the crush of the grain myself. I batch sparge and consistently am 80-85% on my mash efficiency. And my process sounds pretty close to yours.



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Old 12-02-2012, 06:11 PM   #3
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Are you mixing your runnings before taking sample, stratification occurs as the lighter sparge does not mix with the heavier first run.

Are you temp correcting your readings?

Forget about your pre boil readings, are you getting your desired OG in the fermenter?

Are you hitting the correct volumes both pre and post boil?

Have you evaluated your crush?

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Old 12-02-2012, 06:32 PM   #4
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Quote:
Originally Posted by duboman View Post
Are you mixing your runnings before taking sample, stratification occurs as the lighter sparge does not mix with the heavier first run.

Are you temp correcting your readings?

Forget about your pre boil readings, are you getting your desired OG in the fermenter?

Are you hitting the correct volumes both pre and post boil?

Have you evaluated your crush?
The two measured numbers quoted above are the first run (pre-sparge), and then the combined mash + sparge (in the brewpot, well-stirred). I'm guessing the sparge runoff has barely double-digit points. Is that normal?

All of the gravity readings were temperature corrected.

I am reaching my target gravity readings post-boil, but only because I'm dumping in a bunch of DME for the boil.

But I am starting to doubt myself with regards to the crush. I'm using the mill at the LHBS, which I know is questionable to do, but my LHBS is Adventures in Homebrewing, and it looks like what I expect. Here's a picture:



How's that look?
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Old 12-02-2012, 06:58 PM   #5
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Quote:
Originally Posted by joshwoodward View Post

The two measured numbers quoted above are the first run (pre-sparge), and then the combined mash + sparge (in the brewpot, well-stirred). I'm guessing the sparge runoff has barely double-digit points. Is that normal?

All of the gravity readings were temperature corrected.

I am reaching my target gravity readings post-boil, but only because I'm dumping in a bunch of DME for the boil.

But I am starting to doubt myself with regards to the crush. I'm using the mill at the LHBS, which I know is questionable to do, but my LHBS is Adventures in Homebrewing, and it looks like what I expect. Here's a picture:

How's that look?
Temperature correction calculators should come with a warning that states they aren't very accurate over 100* (not sure what temp you took your readings at). As far as your crush goes, it appears there are a few uncracked kernels but from a picture its hard to tell. Pick up the omes that are whole and see if they break. They should require no effort to do so. You can also run your grain through twice to see if that helps.
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Old 12-02-2012, 07:07 PM   #6
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Quote:
Originally Posted by phoenixs4r View Post
Temperature correction calculators should come with a warning that states they aren't very accurate over 100* (not sure what temp you took your readings at). As far as your crush goes, it appears there are a few uncracked kernels but from a picture its hard to tell. Pick up the omes that are whole and see if they break. They should require no effort to do so. You can also run your grain through twice to see if that helps.
I've noticed that, too - the readings I take are mostly in the 80s and 90s, and last night I kept a pre-boil sample around and cooled it to room temperature to make sure it wasn't a problem with that - same adjusted reading. (And I have a refractometer on my list for Santa.. hehe)

And actually, now that you mention it, there are some uncracked pieces, and they do need some pushing to crack. Should there be almost no uncracked pieces, then?
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Old 12-02-2012, 07:24 PM   #7
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Quote:
Originally Posted by joshwoodward View Post

I've noticed that, too - the readings I take are mostly in the 80s and 90s, and last night I kept a pre-boil sample around and cooled it to room temperature to make sure it wasn't a problem with that - same adjusted reading. (And I have a refractometer on my list for Santa.. hehe)

And actually, now that you mention it, there are some uncracked pieces, and they do need some pushing to crack. Should there be almost no uncracked pieces, then?
There should be no uncracked pieces if you are going for efficiency, however the finer the crush the more trouble you MAY have with your run off. That's also a small representative sample, imagine multiply your u cracked kernels by 10-20 pounds depending on your grain bill and it adds up quick.
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Old 12-02-2012, 08:04 PM   #8
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That's a really small picture sample but I see no flour and a few that appear not cracked. IMO that's a pretty crappy crush

What doesn't make sense to me though is your first runnings exceed the desired pre boil and even your sparge runnings aren't that low, many will sparge out to 1.010.

Crush is a concern for sure but somewhat confused with your measurements as well.....

Is your hydrometer calibrated? In distilled water it should be 1.000 at 60F. The paper label will have the actual calibration temp on the very bottom. Are you sure the paper hasn't slipped, it happens.

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Old 12-02-2012, 08:31 PM   #9
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Rereading your post, it appears your using abut 8 pounds in the mash? I don't have the time to plug in numbers but isn't that expecting efficiency in the low 80s? That's a pretty high efficiency for a 5 gallon batch whilst still learning the ropes of all grain.

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Old 12-02-2012, 08:51 PM   #10
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Quote:
Originally Posted by joshwoodward View Post
So I've been doing all-grain for awhile now, and I have 7 AG brews under my belt. Every single one of them has been drastically under the target gravity.

Example: last night, it was a brown ale. I mashed 6.25 lb 2 row, and about .4 lb each of 40L caramel, carafoam, and chocolate malt in 3 gallons of water at 150ish, pH=5.1, then batch sparged with another 3 gallons of 170F water (with a good stir and a 10 minute rest). Target pre-boil OG was 1.043 (assuming only a 68% efficiency), target post-boil 1.052. The first run mash gravity was 1.057, but once I added the sparge wort to the first run, it was only 1.030 (which, mathematically, means the sparge water was basically just plain water). I had to add almost a pound of DME to get the gravity up for my puny 3.5-4 gallon batch. That's about 60% efficiency.

Another example: my last hefe. Target pre-boil was 1.046, target post-boil was 1.052. First run gravity was 1.070 (3.3 gal mash water), but after 4.7 gal of sparge water, the gravity was 1.032. That's 56% efficiency.

And that seems to be the pattern with all of the brews, they all come in drastically under. I've checked the temperature, the crush is good I think, I've used all different sorts of water, I have a cooler with a false bottom and don't get stuck sparges.

I should mention, my goal is time savings and predictability, so buying extra grain to make up for my lousy efficiency isn't a big deal, even going no-sparge would be fine. But, I feel like there's something wrong with my process that's causing this to be happening, and I'd love to correct it.

Any ideas?
In re-reading this I noticed something else: you are mashing in awfully thin. Ideally you want to mash at 1.25-1.5 qts/lb which means you should have only used 2.18-2.6 gallons. Assuming .12gallons/lb or absorption first runnings would have yielded appr. 1.3-1.5 gallons and then a sparge of 6-6.25 gallons to get your pre boil volume of 6.5 gallons +/-

I still stand by my other concerns about crush and the accuracy of your hydrometer though, just wanted to point this out about your process.


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