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Author Topic: When to Start Measuring SG  (Read 1278 times)

Offline Tfwebster

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When to Start Measuring SG
« on: October 04, 2020, 05:59:32 pm »
Using a hydrometer wastes a lot of good beer.* How many days after pitching should I start measuring and how often thereafter?

* OK, I drink it, but still.
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Offline MNWayne

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Re: When to Start Measuring SG
« Reply #1 on: October 04, 2020, 08:59:30 pm »
I brew lagers. My first SG reading is at 10 days.  Then about every 3 days.
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Offline Bob357

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Re: When to Start Measuring SG
« Reply #2 on: October 04, 2020, 11:34:18 pm »
Once the Krausen has receded active fermentation is usually done for all intents and purposes. There's no need to get in a hurry at that point. Another week or so will allow more of the yeast and other particulate to settle out and allow you to package cleaner beer. There's really no reason to waste beer with gravity readings until you're 2 or 3 days away from bottling. A second reading a couple of days later confirm that fermentation is complete if gravity hasn't dropped any further.
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Offline Semper Sitientem

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Re: When to Start Measuring SG
« Reply #3 on: October 05, 2020, 02:02:50 am »
Switch to a refractometer.
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Offline goose

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Re: When to Start Measuring SG
« Reply #4 on: October 05, 2020, 08:20:19 am »
Switch to a refractometer.

But then you will have to use a correction factor to get an accurate gravity reading since the alcohol will throw off the reading.  It will get you close but not exact.  I am not saying don't use one. You can sample during the beer during fermentation with the refractometer to see the trend of gravity reduction.

I just make a bigger batch so that I can take samples and read the gravity with my hydrometer during fermentation to account for this loss as well of the loss I see when I "burp" the yeast and trub out of the cone of my conical.  Plus, I can taste the beer when taking a sample to see how it is progressing and identify any fermentation issues that might be developing and take corrective action.  But wating until the krausen has dropped to take a reading will waste less beer as Bob mentioned.
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Offline Semper Sitientem

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Re: When to Start Measuring SG
« Reply #5 on: October 05, 2020, 11:22:41 am »
Switch to a refractometer.

But then you will have to use a correction factor to get an accurate gravity reading since the alcohol will throw off the reading.  It will get you close but not exact.  I am not saying don't use one. You can sample during the beer during fermentation with the refractometer to see the trend of gravity reduction.

Sure, you have to use both side by side for several measurements to calculate a WCF, but IMO it’s worth the effort. Whether a hydrometer is more accurate is debatable due to the fact that there is a margin of error when reading the meniscus. So, neither is exact, but both are close enough for the home brewer. The OP was looking to save beer. Refractometer uses drops vs. ounces.
Confidunt in cervisia nobis

Scientists believe that the universe is made of hydrogen, because they claim it’s the most plentiful ingredient. I claim that the most plentiful ingredient is stupidity. - Frank Zappa

Offline goose

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Re: When to Start Measuring SG
« Reply #6 on: October 05, 2020, 11:53:24 am »
Switch to a refractometer.

But then you will have to use a correction factor to get an accurate gravity reading since the alcohol will throw off the reading.  It will get you close but not exact.  I am not saying don't use one. You can sample during the beer during fermentation with the refractometer to see the trend of gravity reduction.

Sure, you have to use both side by side for several measurements to calculate a WCF, but IMO it’s worth the effort. Whether a hydrometer is more accurate is debatable due to the fact that there is a margin of error when reading the meniscus. So, neither is exact, but both are close enough for the home brewer. The OP was looking to save beer. Refractometer uses drops vs. ounces.

I don't disagree with you regarding saving beer (from the OP) and am not being critical here.  But being as anal retentive as I am, I always use a hydrometer for accuracy.  I know to read from below the meniscus since I had to do that all the time in my college chemistry courses when I majored in that discipline.
I only waste maybe a couple hundred ml of beer when I take a measurement so I compensate by either making the batch a bit bigger or deal with what I get for ending volume.  I brew to hit my OG rather than a specific volume so if I end up with 4.5 gallons from a five gallon batch I don't sweat it.
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Offline Kevin

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Re: When to Start Measuring SG
« Reply #7 on: October 07, 2020, 09:33:55 am »
I stopped taking FG readings altogether. Experience has given me a good barometer to follow so I only check FG at packaging time.
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Offline erockrph

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Re: When to Start Measuring SG
« Reply #8 on: October 07, 2020, 10:30:48 am »
I stopped taking FG readings altogether. Experience has given me a good barometer to follow so I only check FG at packaging time.
I don't bother taking an FG for most of my beers at all, unless something tastes off or I'm testing something out. I take a refractometer reading at the end of the mash and the end of the boil, and that's pretty much it nowadays.
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Offline John Miliziano

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Re: When to Start Measuring SG
« Reply #9 on: October 08, 2020, 06:30:14 am »
I use the refractometer just to confirm fermentation complete. Stable reading over several days and uses only o a few drops (not concerned about accuracy). then I take the hydrometer reading just before bottling for an accurate measurement.

Offline charlie

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Re: When to Start Measuring SG
« Reply #10 on: October 08, 2020, 06:42:37 pm »
I take an OG from the stuff left in my Thermonator, and I take an FG from the stuff left in the fermentor after I keg. I don't mess with the brew in between that because there's too much chance of contaminating it.

I don't see the point of taking intermediate gravity readings. We never did that at the brewery.

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Offline HighVoltageMan!

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Re: When to Start Measuring SG
« Reply #11 on: October 09, 2020, 10:04:58 am »
I stopped taking FG readings altogether. Experience has given me a good barometer to follow so I only check FG at packaging time.
I don't bother taking an FG for most of my beers at all, unless something tastes off or I'm testing something out. I take a refractometer reading at the end of the mash and the end of the boil, and that's pretty much it nowadays.
I do the same. If I'm brewing for a competition then I take a gravity reading at the end of fermentation, but if you have your brewing technique down pat, you can almost predict the gravity and when it's finished.

Offline erockrph

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Re: When to Start Measuring SG
« Reply #12 on: October 09, 2020, 03:45:20 pm »
I stopped taking FG readings altogether. Experience has given me a good barometer to follow so I only check FG at packaging time.
I don't bother taking an FG for most of my beers at all, unless something tastes off or I'm testing something out. I take a refractometer reading at the end of the mash and the end of the boil, and that's pretty much it nowadays.
I do the same. If I'm brewing for a competition then I take a gravity reading at the end of fermentation, but if you have your brewing technique down pat, you can almost predict the gravity and when it's finished.
To be honest, I doubt I could taste the difference between an IPA that finishes at 1.008 or 1.010 (for example). I drink the beer, not the number. I'm pretty much just brewing for myself, so that's why I don't bother unless I'm troubleshooting something that seems off.

I also break way less hydrometers this way!
Eric B.

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Offline Bel Air Brewing

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Re: When to Start Measuring SG
« Reply #13 on: October 11, 2020, 04:53:24 am »
We at Bel Air Brewing take an OG after the wort has cooled to ferment temp. We will take a FG at kegging time, but it is not a big deal. The taste of the beer tells us what we need to know.

Previously I brewed for 20 years, never took one OG or FG. The beer tasted great, and was less filling. Taste's great, less filling.
« Last Edit: October 11, 2020, 11:40:38 am by TXFlyGuy »