What effect does adding the priming sugar have on a gravity reading?

Discussion in 'General Brewing Discussions' started by Browmore5, Jan 15, 2021.

  1. Browmore5

    Browmore5 New Member

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    I brew half batches from the 5gal all grain beer kits that are commonly available. Mostly to keep the weight down when moving things around by hand - old guy, older back. It also gives me a chance to experiment on the second half by adding some additions, so my batches are 2.5-3.5gals. I try to get as many bottles as I can so I use that last half bottle to put in the cylinder and take a gravity reading instead of drawing it ahead of time. My numbers are usually close,never right on but the beer is always great so I don't follow it too closely as some.
    It says in the ABV calculator to take the final gravity sample before adding the priming sugar, so I just wonder if you take it after what direction would it throw the gravity in? Am I correct in thinking it will increase the reading? Any thoughts by how much the sugar would change it?
     
  2. Megary

    Megary Well-Known Member

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    The short answer is that your ABV will move imperceptibly.

    The long answer would require more info:
    Are you diluting the priming sugar in (pre-boiled) water before you add it? How much water?
    Then math gets involved. *sigh*
    Then you go through all the trouble to determine that your ABV probably moved by less than 0.5%.
     
  3. Nosybear

    Nosybear Well-Known Member

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    To prime, you're adding 2-3 points of sugar. Yes, it increases the FG by those 2-3 points. It then ferments out. I suppose if you wanted to be completely rigorous you could add those points to your OG but the change in the beer, aside from carbonation, is trivial. I would actually suspect, since you're using sugar, priming would take the gravity down by a trivial amount..
     
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  4. Browmore5

    Browmore5 New Member

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    Thanks guys, along the same lines I was guessing - really not that much of a change to the readings. I used 1.65oz in a cup of pre-boiled water to prime about 3.25 gals. To get about a .5% ABV gain would always be nice and it would put me just about right on with BF brew sheet. As long as I'm somewhat close then I feel things are all working as hoped.
    This last batch was brewed in late December from leftovers from the year before with some fresh yeast. Should be an interesting one. The yeast did a great job for a couple of weeks and all is looking very clear which always makes for a good beer. Just bottled it up this morning.
     
  5. Daniel Parshley

    Daniel Parshley Active Member

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    I do both a O.G. and F.G, and BRIX (my toys). The BRIX just because I don't want to waste beer but will come off a few drops to see how things are doing. Try taking the BRIX before and after adding priming sugar and after conditioning. The hydrometer and BRIX are usually within a point of each other. If I have measured right all along, I find the BF recipe tool to be just about spot on.
     

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