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Old 06-20-2010, 12:39 AM   #1
kvbutler41
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Default Specific Gravity Question

Hey guys just started with home brewing and got my first batch going today! It was the Irish Red from midwest.

I messed up when trying to ready the specific gravity however I took a sample from the boiling pot before I added the top up water. I got 1.132 at 80 degrees. I figured since I had 2 gallons in the boiling pot and topped up to 5 gallons could I just average the gravity out...

For example find the specific gravity of tap water, then take that and multiply by 3/5s. Then take the 1.132 I got and multiply it by 2/5s. If I add the two together will it be an accurate measurement?


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Old 06-20-2010, 12:51 AM   #2
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The SG of water should be 1.000. That's kind of the point of the scale. Higher or lower gravity than water. Your tap water could be a LITTLE different since 1.000 is distilled water, but not that much.

Why not just take the SG now? Nothing wrong with that.


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Old 06-20-2010, 03:01 AM   #3
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I doubt it will be an accurate measurement. By the way, congrats on your first batch! I go along with cat; take a reading after it is topped to your final fermentation volume, adjust the temp (if needed) and calculate the starting gravity.
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Old 06-20-2010, 03:14 AM   #4
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You're supposed to take the reading before you pitch your yeast, but it's not going to mess it up doing it after, if that's what you're worried about.
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Old 06-20-2010, 04:34 AM   #5
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To calculate it you have 2g with 1.132 SG. 2 x 132 = # of points of gravity total.
It is now in 5g so (2x 132)/5 = 52.8. Your calculated SG is 1.053. But like Cat says, you can measure it now which will be more accurate.

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Old 06-20-2010, 03:50 PM   #6
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If you take the gravity after adding top up water, remember to mix really well before taking the sample. Personally, I would do the calculation like Got Trub said, rather than wasting another sample.

-a.


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