Frustrated: Always (Well) Below Gravity Targets

duboman said:

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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joshwoodward said:

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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phoenixs4r said:

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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joshwoodward said:

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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joshwoodward said:

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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duboman said:

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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joshwoodward said:

For anyone stumbling across this thread, I wanted to give an update. I found the problem - though I was using water from a number of different places, after some research, I found that it was all reverse osmosis water, which is missing the minerals needed for a good extract. *headdesk* I swapped out the water, and my efficiency went through the roof!

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