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General Category => General Homebrew Discussion => Topic started by: flbrewer on June 09, 2013, 09:51:42 PM

Title: FG and priming sugar
Post by: flbrewer on June 09, 2013, 09:51:42 PM
Should you take FG before or after adding priming sugar to beer? The FG (~1.016) reading today while bottling was quite different than yesterday (~1.013). The beer has been in the fermentor for 2 weeks.
Title: Re: FG and priming sugar
Post by: a10t2 on June 09, 2013, 10:06:24 PM
Before - or if you do it after make sure to subtract the effect of the sugar.

On the other hand, it isn't a really significant difference either way. 4 oz in 5 gal would add 0.0023 SG.
Title: FG and priming sugar
Post by: flbrewer on June 09, 2013, 10:37:17 PM
Hmmm, wonder why the difference. Possibly I read it wrong yesterday as there were a ton of bubbles around the hydro. Also strange I see the number move a bit when it sits for a while.
Title: Re: FG and priming sugar
Post by: morticaixavier on June 09, 2013, 11:09:36 PM
both temperature and residual dissolved co2 will skew the reading. for temp there are tables to consult. for the co2 you can pour the sample back and forth between two containers until it mostly stops foaming up and then take your reading.
Title: FG and priming sugar
Post by: flbrewer on June 09, 2013, 11:17:28 PM
Really don't know why I obsess over the ABV!
Title: Re: FG and priming sugar
Post by: micah h on June 10, 2013, 07:22:22 AM
Really don't know why I obsess over the ABV!

If you're like me it's because you like sharing your brew with friends, and the ABV is one of the first questions they tend to ask about.

Also nonbrewers tend to expect you to know all the answers. But you don't, you're learning. "By you I mean you and me." After my first batch was done I had just followed a recipe and new none of the science behind how I made beer, they all bombarded me with questions and my only response was that I boiled a bunch of stuff and it turned into beer.
Title: Re: FG and priming sugar
Post by: a10t2 on June 10, 2013, 02:25:36 PM
Really don't know why I obsess over the ABV!

Would it help or hurt to know that even if you do the math you don't stand a chance of getting within 0.1% ABV?
Title: Re: FG and priming sugar
Post by: micsager on June 10, 2013, 02:49:11 PM
both temperature and residual dissolved co2 will skew the reading. for temp there are tables to consult. for the co2 you can pour the sample back and forth between two containers until it mostly stops foaming up and then take your reading.

+1, and let it sit for an hour or so........
Title: Re: FG and priming sugar
Post by: gymrat on June 10, 2013, 02:55:13 PM
Really don't know why I obsess over the ABV!

If you're like me it's because you like sharing your brew with friends, and the ABV is one of the first questions they tend to ask about.

Also nonbrewers tend to expect you to know all the answers. But you don't, you're learning. "By you I mean you and me." After my first batch was done I had just followed a recipe and new none of the science behind how I made beer, they all bombarded me with questions and my only response was that I boiled a bunch of stuff and it turned into beer.

I hope I never stop learning. That is part of the fun of brewing.
Title: Re: FG and priming sugar
Post by: narvin on June 10, 2013, 04:54:02 PM
Before - or if you do it after make sure to subtract the effect of the sugar.

On the other hand, it isn't a really significant difference either way. 4 oz in 5 gal would add 0.0023 SG.

That's about what he measured, so the difference was probably due to measuring after adding the sugar.  The standard 5oz that comes with kits is almost exactly 3 points in 5 gallons.

Of course, when you disregard the priming sugar, you're ignoring the extra alcohol produced.  On the other hand, you also have to take into account the dilution when you boil the sugar in some water.  The bottom line is, you're just making an estimate, so relax  :)
Title: FG and priming sugar
Post by: flbrewer on June 10, 2013, 05:04:47 PM
Well said!