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Home Brew Forums > Home Brewing Beer > All Grain & Partial Mash Brewing > Missed OG on first All Grain
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Old 12-31-2011, 06:31 AM   #1
hough77
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Default Missed OG on first All Grain

Brewed a Hefe AG kit from NB, OG was supposed to be 1.049, came out to 1.032 with 5.25ish gallons of wort after boil.
5.5# weyermans German Pale Wheat malt
4# German Pilsner
I used Brew Pal for IPhone since there are no strike/ sparge calculations in the instructions.

10g Home Depot mash tun with 24in SS braid.
Top cut off keg for kettle.

9.5# grains mashed @ 152* for 60 with 3.6g of strike water
Single batch sparge with 4.3g @ 177* for 10 mins
Filled bucket fermenter to 5.25g and pulled a low OG.
I boiled 2# of Light DME and 1# of light Belgian Candy in 1g of water for 20 mins and mixed with wort to get a Gravity of 1.050 ( winged it on the DME an Candy)
So where did I mess up?

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Old 12-31-2011, 12:20 PM   #2
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did you take a reading after you ran off your mash tun but before boiling?
how much did you collect in your kettle before boiling?

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Old 12-31-2011, 12:48 PM   #3
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I've never bought grain online. Being a noob, however, I have learned that the crush of your grain definitely DOES affect your efficiency. My first few all grain batches I was low and thought it was something I did. Then I found a new LHBS that I seemed to get a much finer crush with their mill. I gained 10-15% on that batch and have been consistant since then. Like I said, I'm a noob, but check your crush. It made a huge difference for me.

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Old 12-31-2011, 02:41 PM   #4
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I'm still working out efficiency issues myself. I think the kits assume a fairly optimistic percentage; after all they are trying to make money. Track your efficiency and variables like the crush of the grain, water source and water/grain ratio. Also, don't settle for low gravity! Just keep some pale DME or LME on hand and bump it up to the target. I've had great success with this when my gravity is low. It might not be the exact recipie, but then again neither was a 1.032 SG brew right??!!

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Old 12-31-2011, 02:55 PM   #5
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Your crush is going to greatly affect your efficiency. Buying a mill was one of the best purchases I've made. My local homebrew shop's crush gave me ~65% efficiency. I'm now ~80% with my crush at home. You'll hit your numbers when you can plan accordingly. And that takes time. Everyone's setup is different. Everyone has different preboil volumes, water:grist ratios, etc... You'll find yours - just keep trying!

And in the end, it's all beer.

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Old 12-31-2011, 02:55 PM   #6
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The reason for a pre-boil gravity and volume reading is to be able to adjust your gravity with a little DME. Now missing your gravity by 17 points means there are a few process issues to work out. For example, slow down your run off, have a finer grain crush as mentioned above.

If you do want to adjust with DME here is what I do. I posted this earlier in the week for another brewer.

Quote:
Originally Posted by lutherslagers View Post
You want to keep a light DME (dry malt extract) on hand. It will allow you to do gravity adjustments using the following formulas from Ray Daniels' book designing great beers. Here are the formulas and then I'll explain them:

Formula 1: Pre-boil GU x Pre-boil volume / desired post-boil volume = the gravity of your wort after concentrating the sugars through boiling.

I need this formula to figure out what my gravity will be when I'm done boiling. I may be spot on and no gravity adjustment is needed. I may be way off and need to use DME in the boil to hit my desired gravity.

Before I break down the formula let me explain what a GU is. It stands for gravity unit. Its essentially the last two digits of your specific gravity. The GU of a 1.050 beer is 50. The GU of a 1.085 Dopplebock is 85. Mathematically its ((specific gravity x 1000)-1000), but who likes math.

The first part of the equation comes from values you will measure after you finish mashing and run everything into your kettle, BUT BEFORE YOU START BOILING. So you're measuring your gravity of the total volume you collected in the kettle (don't take this reading from a mash tun sample, you're gravity will be higher at the beginning of run off and lower at the end of run off). You're also measuring the total volume you collected.

Let’s say you’re readings here were 1.048 (or 48 GU) and 7.25 gallons wort. 7.25 x 48=348.

Now divide 348 by your desired volume after you’re done boiling. For me this is 6 gallons (as an aside I leave 1/2 a gallon behind in the kettle, move 5.5 gallons to my carboy and after fermentation I leave 1/2 a gallon in the carboy and move 5 gallons of trub and debris free beer to a keg)

So now we have 348/6 = 58 or a specific gravity of 1.058 after the boil. Great… but I wanted to brew a 1.065 beer. So this is where we go to Formula #2. Note that you should have used formula #1 before you started boiling your wort.

Formula 2:
(Target GU x Target Volume) - (Pre-boil GU x Pre-boil Volume) / Extract per lbs.

In the first part of the equation I'm applying the volume I want and the specific gravity I want after the boil. So I want 6 gallons of wort after the boil and my recipe is a 1.065 beer. So my first number is 6x65 = 390.

So now we have:
390 - (Pre-boil GU x Pre-boil Volume) / Extract per lbs.
The second part of this equation is identical to the first part of the first equation above. We already know that number, it is 348.

So now we have:
(390 - 348) / Extract per lbs.

Extract per lbs. for Briess light or pilsen DME is 45.

So now we have
(390 - 348) / 45 = 0.93

I need 0.93 lbs of DME added to the boil to hit my target gravity of 1.065.
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Old 12-31-2011, 05:29 PM   #7
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Quote:
Originally Posted by lutherslagers
did you take a reading after you ran off your mash tun but before boiling?
how much did you collect in your kettle before boiling?
I didn't take a reading, and after batch sparging, I collected just over 6g. I measured using a 1g pitcher. I pulled a gallon of first runnings and dumped it back in and the collected what was in the tun and it looked very thin, but it was mostly wheat so I didn't think anything of it.
After the boil I had just over 5g siphoned into the fermenter.
So if a take a gravity reading pre boil, I do it with the wine their and hydrometer using hot wort just like the finished product? No refractometer here.
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Old 12-31-2011, 05:36 PM   #8
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Quote:
Originally Posted by lutherslagers
The reason for a pre-boil gravity and volume reading is to be able to adjust your gravity with a little DME. Now missing your gravity by 17 points means there are a few process issues to work out. For example, slow down your run off, have a finer grain crush as mentioned above.

If you do want to adjust with DME here is what I do. I posted this earlier in the week for another brewer.
The crush looked ok, I was supposed to get that book for Xmas and never got it.
I will have to go over that formula a few times. (hate math, but love it when I get it)
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Old 12-31-2011, 05:49 PM   #9
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I've done partial mashes up to this point and had no problems hitting gravity.
The fermenter is bubbling away ferociously so there will be alcohol. I'm more annoyed that it won't have the body or mouthfeel that it should after spending all that time brewing it.
The only thing I could think I did wrong in the process is miss judge amounts of water (but I Doubt it), and ran off the mash to fast.

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Old 12-31-2011, 07:34 PM   #10
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Quote:
Originally Posted by hough77 View Post
I didn't take a reading, and after batch sparging, I collected just over 6g. I measured using a 1g pitcher. I pulled a gallon of first runnings and dumped it back in and the collected what was in the tun and it looked very thin, but it was mostly wheat so I didn't think anything of it.
After the boil I had just over 5g siphoned into the fermenter.
So if a take a gravity reading pre boil, I do it with the wine their and hydrometer using hot wort just like the finished product? No refractometer here.
One tip that'll be easy. Make a calibration stick, rather than use a 1 gallon pitcher to measure. Take 3 feel of CPVC and a sharpie and mark off every 1/4 of a gallon or so.

You don't need a refractometer to do a pre-boil gravity reading. After your are done running off from the mash tun, take 3/4 cup of wort from your kettle. Put that in a metal mixing bowl and put that metal mixing bowl into some ice water and swirl it around. You'll chill the temp down to 68 F (or whatever your hydrometer is calibrated for) in less than a minute. Pour that into your hydrometer tube and take a reading.

Also, stay positive you still made beer.

A final note, but I do want to keep this straight forward. Wheat and Rye are known for having sticky or stuck mashes and many folks add rice hulls to help with sparging. It's possible you left a lot of wort back in your mash tun do to this stickiness which could account for your low gravity. But that fact that you collected 6 gallons from the mash tun leaves me skeptical that you had this issue.
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