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Efficiency and age of grain?

sma

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Dec 14, 2011
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Location
Connecticut
I've been all grain brewing for nearly 2 years and every batch (30+) have come out very close to the final gravity (post boil) that the BeerSmith 2 calculates however for the past three or four batches the SG has been 10+ points lower than it should be.  Example, my target final gravity on my brown ale should be about 1.056 but I'm lucky if I hit 1.042.  My lager that I did last weekend should have been 1.056 but to achieve that I had to add 1 1/2 pounds of DME. 

Nothing in my brew process has changed but something must have.  My grind setting is the same on my Monster Mill.  The water volume is correct.  The only thing is my grain is probably close to 9 months old.  I store it in a big storage tub but it is not air tight, could that be the culprit? 

Looking for suggestions on what to tweak. BTW... I just used up the last of the old grain and will be tearing into new 50 pound bags soon.
 
You're talking 25% drops in efficiency, which seems high if the process has not changed. 

Is it possible something glitched in BS2, making the estimates wrong to begin with?  EE% or Batch Volume get changed? 

Maybe compare Equipment Profile to last batch that went to plan? 
 
Also double-check the calibration of your instruments, particularly those used for gravity measurements. The jump (backwards) in efficiency looks too large to blame on aging grain. That change would be much more gradual UNLESS - you've got bugs eating the good stuff out of your grain - take a close look when you get a chance.
 
Was there a lot of dust on the grain indicating that a hoard of bugs came and ate all off the good stuff? This is highly unlikely BTW.

I'd bet beersmith software changed somehow. If you post up a recipe file (export as .bsmx) that might be a good place to start.
 
As a test I will very closely monitor my brew this weekend.  I basically have three recipes; A lager, A brown ale and an IPA.  The Lager is tried and true and that one was off by quite a bit and had to add DME to bring the FG up.  That recipe hasn't changed at all in over a year and a year ago I was hitting close to the target FG.  My brown ale is a relatively new recipe so I can't really use that as a test case to refute or support the BS program.  This weekend I will use my oldest recipe which is an IPA and I will closely monitor all.

I'm going to monitor very closely the temperature as well.  Let's see what this weekend brings.
 
Also keep in mind that grain is typically only harvested once a year.
 
56 to 42 is huge
I would check the calibration of my themometer used in the mash before I accused the grain. especially if it was the same grain I had been using all along. another thing to think of is if you had changed sparging technique? both of those could cause a 25% swing
 
I guess if nothing has changed then nothing would have changed. Something has just, we just don't know what it was.
The first, since it's in the main topic: i am not sure but it may be worth considering, I would tend to believe that as malt ages it looses moisture and reduce the plumpness of the grain. meaning the gap for the mill may need to be squeezed more for older malt to obtain the same results.
Another possible cause would be conversion temperatures & time mashed. Is your thermometer lying to you?
One other possible cause would be pH. If the pH doesn't drop in the mash (5.4 is a pretty good number) (5.7 is not) efficiency will be effected.
municipal water supplies do change from time to time

I hope this helps, isn't brewing fun?
 
+1000 to municipal water supplies do change from time to time.
  I've seen the water change from one day to the next  I.E.  GH and temporary hardness.
I think that the changes come from the water towers and there levels. for example the city may send more water from one tower one day and then pump water strait from the treatment plant the next, for what ever reason. just an assumption.
 
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