Author Topic: Target vs. Actual OG  (Read 570 times)

Offline JonLuskin

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Target vs. Actual OG
« on: October 20, 2015, 04:45:41 PM »
Hello!

My buddy and I brewed six batches on Sunday. I found that with every batch, we fell short of the target OG. Here are the deltas of the target vs. actual OG for our six brews.

-0.004
-0.004
-0.002
-0.008
-0.002
-0.004

So, I have a few questions on the subject:

1.) Why is this happening?
2.) How do I fix it?
3.) Does it matter?
4.) At what point is the delta negligible? 0.001? 0.002? 0.010?

Offline morticaixavier

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Re: Target vs. Actual OG
« Reply #1 on: October 20, 2015, 04:51:46 PM »
Targets are estimates based on a variety of variables. Are you brewing all grain or extract?

if all extract than there are only a couple of possible causes:
1) Inadequate mixing leading to stratified wort and an inaccurate sample
2) The extract that you were using was slightly different than the extract used in the recipe
3) your volumes were not exactly right.

if all grain it's more complicated because there is the potential extract of the particular batch(es) of malt(s) you are using, the nature of your system and your water. Plus all of the same issues above associated with extract only batches.

so where did the target come from?
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Offline dilluh98

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Re: Target vs. Actual OG
« Reply #2 on: October 20, 2015, 04:52:27 PM »
Quick list: properly and recently calibrated thermometers, hydrometers, refractometers?

I honestly wouldn't sweat a 0.004 difference - just take good notes and adjust accordingly for next time. I'd challenge anyone to tell the difference between two exact recipe beers that had an OG difference of 0.004. Assuming same FG, that's around 0.5% ABV difference.

Offline pete b

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Re: Target vs. Actual OG
« Reply #3 on: October 20, 2015, 04:52:44 PM »
Hello!

My buddy and I brewed six batches on Sunday. I found that with every batch, we fell short of the target OG. Here are the deltas of the target vs. actual OG for our six brews.

-0.004
-0.004
-0.002
-0.008
-0.002
-0.004

So, I have a few questions on the subject:

1.) Why is this happening?
2.) How do I fix it?
3.) Does it matter?
4.) At what point is the delta negligible? 0.001? 0.002? 0.010?

I think people will want to hear your brewing procedures before they feel they can help.
For starters:
Have you checked the calibration of your hydrometer and thermometers?
Did you measure water volumes accurately.
Did you weigh your own grain or double check yourself if not.
Did you mill your own grain.

BTW welcome to the forum!
Don't let the bastards cheer you up.

Offline 69franx

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Re: Target vs. Actual OG
« Reply #4 on: October 20, 2015, 05:26:56 PM »
Are these your first batches, or have your deltas been smaller in the past. If you are just starting out, you need to figure out your equipment and process. If it's a new development, what have you changed recently?
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Offline toby

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Re: Target vs. Actual OG
« Reply #5 on: October 20, 2015, 06:03:28 PM »
1.) Why is this happening?

Could be lots of reasons.  Perhaps your efficiency is different from that assumed by the recipe or recipe calculator.  Maybe your water chemistry/pH is also effecting it.  Maybe your grain crush is a little off.  Maybe your hydrometer/refractometer is slightly off.  Etc.  Etc.

Quote
2.) How do I fix it?

Need to know more info about your recipe source and process, honestly.

Quote
3.) Does it matter?

That's probably more a function of the finished product.  If your FG comes in at roughly the same delta under target, then you can start to suspect your measuring equipment or readings.  How does it taste?  If it tastes good, RDWHAHB.

Quote
4.) At what point is the delta negligible? 0.001? 0.002? 0.010?

Probably a function of the taste and strength of the beer.  If you got 1.101 when your target was 1.105, you might not notice.

Offline duboman

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Re: Target vs. Actual OG
« Reply #6 on: October 21, 2015, 05:49:22 PM »
Great input so far and a big +1 to ensuring your measuring devises are properly calibrated and readings are temp corrected!

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Offline charles1968

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Re: Target vs. Actual OG
« Reply #7 on: October 21, 2015, 06:11:03 PM »
The efficiency assumed by whatever brewing software you use is likely to be different from the efficiency your setup achieves. Use the average delta to figure out your average efficiency, then input that into your next recipe and you'll be on target.

Does it matter? Yes if you're out by 0.004 as it's enough to affect the taste of the beer. 0.001 wouldn't matter.

You can also look for ways to raise your efficiency - there are lots of tips all over every brewing forum/blog.

Offline smokeymcb

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Re: Target vs. Actual OG
« Reply #8 on: October 21, 2015, 06:25:48 PM »
I'm of no help but, 6 batches in one day?? Kudos to you buddy...
Anyone got a lighter??

Rob C.