Low OG?

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Low OG?

Postby ebeer » Sun Nov 02, 2003 4:54 pm

I use the calculator on this site religously, and tend to have my OG come out on the low side of the predictions. For example the IPA I made today was 1.057 with calculator predicting 1.064. I'm clearly within the guidelines for an IPA (1.050 to 1.075). My has always turned out well, I'm just curious why all my batches are lower than the calculator predicts and is this something I should even be concerned with? Thanks in advance for any assistance. Info on my last IPA can found by searching recipes for "Lotsa Hopsa".
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A couple

Postby fitz » Mon Nov 03, 2003 4:11 am

There could be a couple reasons.
One counld be the efficiency of your system, if you do all grain.
If you do malt extracts, it could be the difference of the extracts strength.
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Mash Efficiency

Postby Raydownunder » Mon Nov 03, 2003 12:29 pm


If you are using all grains in your recipes you will notice that the mash efficiency prompts 72%. I would suggest you change that to say 65% and adjust the grain bill to suit and you will be spot on. All my single infusion mashes are calculated at 65% for my set up and each batch is spot on.

Another reason might well be the grains are not cracked enough, check that the grains are well cracked.

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Theory vs Reality

Postby Dr Strangebrew » Mon Nov 03, 2003 1:26 pm

I looked at your 'Lotsa Hopsa' recipe.
Your recipe indicates that you used 8lbs of 'light liquid extract.' Theoretically, you would hit the target gravity calculated by beertools if the extract potential of your brand of extract is the same as the'generic' liquid extract set up by beertools calculator. If your brand of extract had a lower extract potential than the one provided in beertool's calculator your actual results would be lower than that of the calculator. This is what I think happened here. Not a big deal, just use a little more extract.

Then again, assuming your extract potential is the same as the calculator. From what I understand dextrine malt and crystal malt do not have enough enzymes to convert their starch. They need to be mashed with a base malt with 'surplus' enzymes so that their starch can be converted into sugar. Assuming that otherwise they would each have an extract potential of .034, and you had a mash efficiency of 70% they would contribute .008 gravity points to your wort, so theoretically a recipe with a predicted OG of 1.064 would have a value of 1.056 if the dextrine and crystal malts didn't contribute to the OG. Hope this helps.
I would say, either your extract's actual potential is different than that of beertools, or dextrine and crystal malts didn't contribute as much as predicted, either way, a solution is to add a little more extract, or keep good records so that over time you can come up with a better extract potential for your extract.
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Crystal malts

Postby Freon12 » Mon Nov 03, 2003 4:15 pm

I was always under the impression that Crystal malts can steeped and need not be converted due to the fact that they are converted during kilning and "Crystalized". The water needs to be warm enough to rinse the sugar out of the grain. True?

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How much water evaporates?

Postby bigdosgood » Tue Nov 04, 2003 8:35 am

I was advised by a long tm brewer that the amount of water is an important part of the OG. Beer tools is calculating based on simple math, but the reality is that if you don't have the same amount of water left, it will be off as in my last batch. I didn't boil it down long enough before adding the hops. I noticed it was about 3/4 of a gallon more than in the predictions.
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You're right

Postby Sisu » Tue Nov 04, 2003 6:17 pm

You don't need to mash crystal malts... just steep them.
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