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Old 05-26-2012, 10:59 PM   #1
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Default low OG

So i spent most of today brewing up what was supposed to be a clone of weidmer brothers x-114 citra IPA.

10.5# U.S. 2 row
.5# C20
.5# C40
.5# Carapills
Their site says that they use C30 but my LHBS didn't have any.
I'm brewing on a 10 gallon system that I made with false bottom, site glass, brewmometers and the works.
My efficiency is usually around 72 percent. So the projected OG from promash was 1.062, damn close to the Weidmer's.

I mashed in with 3 gallons at 162, settled at 152 and went down to 150 after a 1 hour rest. I mashed out and collected 1.5 gallons (I did not ramp it up to mash out temp because the mash was already at a good temp).
I then flysparged 5 gallons for 15 min at 175. Collected 6.5 gallons.
I did a 1 hour boil with 4 hop additions coming to a total of 3 oz plus 2oz at knockout. When I siphoned into a 5 gallon carboy I filled it to the 5 gallon mark and still had about a half gallon left in the kettle. Nice yield right?
The problem is that my OG came out to 1.042
I know that there is not much I can do now but I just can't figure out why my gravity came out so low.
Did I over sparge?
was my boil not long enough?
would the fact that I had a finishing volume of 5.5 gallons really dilute the wort that much?

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Old 05-26-2012, 11:56 PM   #2
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I can see a number of potential problems
How did you mash out?
You drained the initial runnings before starting the sparge? This is a no no with fly sparging.
You fly sparged for 15 min at 175? Fly sparging takes much longer than that to be successful and you cannot do a fly sparge starting with an already drained grain bed.
You collected too much wort during the lauter (or you didn't boil off enough during the boil). This will reduce your efficiency.

Ending up with 5.5 gallons instead of 5 will reduce your OG by 10%

-a.

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Old 05-27-2012, 12:02 AM   #3
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With Brewsmith calcs and 5.5 gallons into the fermenter, it looks like your actual mash efficiency was about 53%. Having an additional 1/2 gallon and 72% mash efficiency would have taken it to 1.057.

Couple of questions:

Is the grain source the same? I've found that getting grain from different sources (LHBS vs NB) for instance has made a big difference in efficiency for me. I have my grain crushed for me and I think the crushes can differ alot between sources.

Did you confirm conversion with an iodine test? I've actually had some mashes that didn't convert fully after an hour. Letting them go another 1/2 hour or so allowed them fully convert.

Since I've had problems with low and unpredictable efficiency in the past, I've invested in a refractometer. What a great tool. At least you can know with less effort pre-boil whether you should make any adjustments (like add DME or adjust the boil rate). It's even easy to take measurement throughout the boil to adjust the speed of the boil-off to get to the right target gravity.

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Old 05-28-2012, 06:12 PM   #4
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Thanks for the replies and sorry for the delayed response.

Quote:
How did you mash out?
You drained the initial running's before starting the sparge? This is a no no with fly sparging.
You fly sparged for 15 min at 175? Fly sparging takes much longer than that to be successful and you cannot do a fly sparge starting with an already drained grain bed.
Without the aid of a gravity feed I mashed out using my pump.
I also have to use my pump to sparge, which does not have any speed control so it comes out at about 7.5 gallons a min (I'v tried adjusting the valve).
So at what point during the mash out do I start sparging and how can I reduce the flow to what amount of sparge time?
Also, should I always leave the kettle uncovered for the boil (in the past I have had too much boil off so I have gotten in the habit of leaving the kettle half covered)?

Quote:
With Brewsmith calcs and 5.5 gallons into the fermenter, it looks like your actual mash efficiency was about 53%. Having an additional 1/2 gallon and 72% mash efficiency would have taken it to 1.057.

Couple of questions:

Is the grain source the same? I've found that getting grain from different sources (LHBS vs NB) for instance has made a big difference in efficiency for me. I have my grain crushed for me and I think the crushes can differ alot between sources.

Did you confirm conversion with an iodine test? I've actually had some mashes that didn't convert fully after an hour. Letting them go another 1/2 hour or so allowed them fully convert.
My overall efficiency from averaging my brews together is usually around 72 percent so my projected OG was 1.062. But for this particular brew my efficiency did indeed go down into the 50's.

I got all of the grain from my LHBS that I have been going to for over a year now and have never had any problems with efficiency or a bad crush (the crush is great. they have a serious mill). I did however get the grain milled about five days before I actually brewed. The grain of course stayed in a stapled shut brown paper bag in a cool and dry place. But it did sit around for a little while.
I did not do an iodine test. After finding full conversion after an hour with at least 20 batches I have kind of trusted in my system, so that may very well be part of it.

~D
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Old 05-28-2012, 06:36 PM   #5
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+1 on a refractometer. I know you are just trying to get a handle on the reason for the low sg right now and I'd be asking the same question BUT for the future, when odd things like this happen, you can test toward the end of the boil and add a little dme/lme. Sounds like you normally hit your target so this would just help iron out flukes and a few session beers.

I feel your pain though, I usually hit 70 also and only hit low 60s on a batch the other day. And that's with all my equip calibrated in Beersmith. I think it was a combo of too much water and a slightly stuck sparge near the end of my batch sparge. Didn't notice the remaining liquid until I was cleaning out the cooler afterward. There's always something to throw a wrench into things lol.

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Old 05-28-2012, 09:50 PM   #6
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Quote:
Originally Posted by CBMbrewer View Post
Without the aid of a gravity feed I mashed out using my pump.
I also have to use my pump to sparge, which does not have any speed control so it comes out at about 7.5 gallons a min (I'v tried adjusting the valve).
So at what point during the mash out do I start sparging and how can I reduce the flow to what amount of sparge time?
Also, should I always leave the kettle uncovered for the boil (in the past I have had too much boil off so I have gotten in the habit of leaving the kettle half covered)?
Well, I do a mash out, and fly sparge, and I also do a thick mash like you, but I use gravity rather than a pump.

For English beers (which accounts for about 90% of my brewing), I dough in using 1 qt per lb. For American beers, I use 1.25 qt per lb, and for lagers, I use 1.5 qt per lb. I mash the English beers for 90 minutes at 150F. Other beers get mashed for 60 minutes at 152 - 153F. At the end of the mash, I do a mash out by adding about 5 - 6 qt near boiling water and stirring it in really well. For a thick mash, this raises the grain temperature to about 165 - 168F. For a thinner mash, the grain bed temp is raised to the low 160's.
I then leave the mash out for 15 minutes before vorlaufing, and then starting the sparge. I do not drain the first runnings before starting the sparge.
I then sparge by slowly adding the sparge water, and draining into the kettle. This usually takes me about 60 minutes for a 5g batch, but may be as long as 90 minutes for a high gravity batch. During the sparge, I monitor the gravity of the runnings using a refractometer. If the gravity drops below about 1.008 before I have collected my pre-boil volume (which it usually does for brews with an OG < 1.050), I stop the sparge, and add water to achieve the pre boil volume.
Depending on what equipment I am using, I achieve 80 - 85% mash lauter efficiency using this method. If I were to sparge in 15 minutes, my efficiency would drop considerably, and I would almost certainly collect excess tannins due to the channeling.

-a.
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Old 05-28-2012, 10:21 PM   #7
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I wouldn't worry about mash-out, it really comes down to a matter of preference. I think the #1 thing that went wrong was the short sparge. it should have been at least 4x as long... My SOP for homebrewing is a 45 minutes mash at 156-158, vorlauf for 5 minutes or so until the wort is fairly clear, begin runoff at a speed to reach kettle volume in 60 minutes. As soon as runoff begins, start introducing sparge water over the grain bed. I don't do a continuous sparge myself, I just get it all into the MLT in the first 5-10 minutes... simply a process difference, but the effect is the same.

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