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Old 09-09-2007, 04:28 PM   #1
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Default Pre-Boil and OG Adjustment Advice Needed

Yesterday I brewed a batch of beer and was really hitting my numbers! Mash temps and extraction pre-boil specific gravity was right on. But after the boil, my OG as a few points below my target OG. What could I’ve done to increase my OG during the boil?

Cheers,
Gary

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Old 09-09-2007, 04:31 PM   #2
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Boil for longer to increase the concentration or increase the preboil gravity by using more grain or increasing effeciency.

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Old 09-09-2007, 05:23 PM   #3
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Actually, if you hit your preboil gravity like you said, you'd hit your post boil also. You don't lose sugar. Now, maybe you just didn't boil off as much water as you expected leaving you with more volume and less sugar. If that's the case, you can just keep boiling. However, it's not horrible to miss up or down by a few points. If you really want to hit the numbers, you can use an extra pound or so of grain next time or have some DME on hand to bring the gravity up.

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Old 09-09-2007, 09:52 PM   #4
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Yeah, I'm using Beersmith and I have my evaporation rate set at 15%. I might lower that percentage to see if that makes a difference.

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Old 09-09-2007, 10:19 PM   #5
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Quote:
Originally Posted by gfranks7807
Yesterday I brewed a batch of beer and was really hitting my numbers! Mash temps and extraction pre-boil specific gravity was right on. But after the boil, my OG as a few points below my target OG. What could I’ve done to increase my OG during the boil?

Cheers,
Gary
As Bobby_M suggests, it sounds like you are being a little optimistic with your efficiency and you need to use a little more grain and although technically you shouldn't loose any sugars during the boil, the sticky condenasation that I sometimes get on the ceiling near the back door suggests otherwise, throttling back the boil too may help. Some people are finding that this also rounds off hop bitterness and improves hop flavour. I'd agree.
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Old 09-10-2007, 03:07 PM   #6
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Did you measure your final volume? This will tell you what your evaporation rate is and then you can use that to guide how long to boil in order to hit your post-boil OG. There is variability in this depending on your heat source and how strongly you boil. With my Cajun Cooker I can get from 13.5% with a barely ticking over boil to 17.8% if I rock and roll. This can really change your final OG if you boil the same amount of time! Sugars do not evaporate so if you hit your pre-boil gravity you were on track to hit your targeted OG, just need to hit your final volume accurately.

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Old 09-10-2007, 05:26 PM   #7
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Unfortunately I didn’t measure my final volume before racking it into my fermenter. That being said, the racked wort volume was close to what I expected. I think I’ll back down my evaporation rate some and on my next batch, I’ll measure my post boil volume to dial in my evaporation rate… Hopefully that will get me close.

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