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Old 05-27-2010, 12:53 AM   #1
billc68
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Default Take your OG reading before adding yeast... why?

I am sure I am not alone in saying, I repeatedly forget to take a hydrometer reading before adding my yeast.
Does it really make much difference if I take the reading immediately after adding yeast? especially if i stirred after adding the yeast???

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Old 05-27-2010, 12:59 AM   #2
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I've taken one before and after pitching just to see what would happen and I measured no difference.

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Old 05-27-2010, 03:52 AM   #3
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Because OG is a measure of sugar particles in the yeast that cause changes in buoyancy of the hydrometer. Adding yeasts also can change the buoyancy of the hydrometer reading to make it read higher than it should be.

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Old 05-27-2010, 03:57 AM   #4
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Quote:
Originally Posted by onemanlan View Post
Because OG is a measure of sugar particles in the yeast that cause changes in buoyancy of the hydrometer. Adding yeasts also can change the buoyancy of the hydrometer reading to make it read higher than it should be.
Yeast doesn't go into solution, so it wouldn't change your gravity reading at all. To me, the main reason would be to not waste the little bit of yeast you'd have in your sample vial. That would be about it.
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Old 05-27-2010, 09:59 AM   #5
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But even if the little bit of yeast, 5-20 grams, did go into solution, would that really make much difference in your reading? I can see adding a half quart or yeast. But as the poster above said, they don't dissolve, so maybe they have zero affect on the reading.

I am sure if I forgot and took my reading the next day there would be a difference as the yeast have been consuming sugar.

Anyway, no big deal, I just get so mad at myself when I forget to take a reading before adding yeast... an old habit from the canned kits days where I never used a hydrometer, cause the OG should be the same every time.

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Old 05-27-2010, 02:10 PM   #6
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Quote:
Originally Posted by billc68 View Post
But even if the little bit of yeast, 5-20 grams, did go into solution, would that really make much difference in your reading? I can see adding a half quart or yeast. But as the poster above said, they don't dissolve, so maybe they have zero affect on the reading.
Solution is different than suspension. Solids have to dissolve to go into solution. Yeast only go into suspension.
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Old 05-27-2010, 02:30 PM   #7
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I make 1/2 gal. starters, so taking the reading before adding all that liquid, is not a true reading. I sanitize the hydrometer and wine thief and take a sample, read it, and splash it back in. Just a little extra aeration Actually, from a sanitation stand point, the wort is inoculated with yeast at that point, so it is safer to muck around in it than before pitching.

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