So im working on a problem that has surpassed my knowledge. Today i brewed a batch of Belgian golden we were looking for a sg of around 1080. Our pre boil gravity read 14.5 plato after boiling off 1.5 gal and adding 32 oz of liquid beat sugar out sg read out on a hydrometer as 1052 and 13 plato on the refractometer. This stumps me, after a volume reduction and addition of further fermentables how can the gravity reading drop? Any insight on this issue would be appricated
Mysterious gravity drop
- Thread starter red96jeep
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chickens4life
Well-Known Member
did you take your preboil reading after collecting all of your wort and mixing it well? if the sample contained more first runnings than second runnings it would be much stronger than the average gravity of the total run off.
That's all i can think of
That's all i can think of
chickens4life
Well-Known Member
Other than that I don't see anything that could have caused a loss of total sugar, it makes no sense to me at all.
Maybe the liquid beat the sugar right out of the pot?
Most odd errors of measurement come down to instrument error, reading error, or incomplete mixing. In your case, the later FG was verified with 2 instruments, and the boil should have taken care of mixing the wort well, so that must be correct. The initial measurement was done with only 1 instrument, and one that we assume would work based on its calibration with your hydrometer, so that's all out, too. That leaves mixing of the wort for the preboil measurement. Are you sure the various runnings were properly stirred up in the pot?
Most odd errors of measurement come down to instrument error, reading error, or incomplete mixing. In your case, the later FG was verified with 2 instruments, and the boil should have taken care of mixing the wort well, so that must be correct. The initial measurement was done with only 1 instrument, and one that we assume would work based on its calibration with your hydrometer, so that's all out, too. That leaves mixing of the wort for the preboil measurement. Are you sure the various runnings were properly stirred up in the pot?
OP
OP
red96jeep
Well-Known Member
yes, i am absolutely sure the mixing of the wort after runoff was done completely, not only was the wort ran into the kettle using a tube filling from the bottom up, it was also stirred and allowed mixing time before the sample was taken. im wondering if using a liquid sugar solution in the boil as opposed to the traditional hard sugar may have been the issue? this was my first time using the liquid solution, is it supposed to be added during fermentation only?
Did you make the liquid, or did you buy it premade? Either way, do you know the exact amount of sugar and water in the mix? I suppose if it were dilute enough, you're right, it could be the explanation. I imagine it would have to be pretty dilute to account for the numbers you saw.
Did you cool the samples to under 100 degrees before reading and then correcting for temperature? I know the temperature correction tables go up to higher temperatures, but they are notoriously inaccurate over about 90 degrees. Under 90 degrees, you can get a good reading by reading the hydrometer and then using temperature correction. Or did you use the refractometer only for the preboil gravity?
Assuming these are marked as fluid ounces (being a liquid and all), you added a quart of 1.033 liquid. Did you add them pre or post boil? Either way, it's actually going to bring your gravity down, but not nearly by what you saw. There's also no way these will add 12 points to your gravity. So at least we know why you didn't get to 1.080, but it still doesn't explain why your gravity dropped after boiling off 1.5 gallons (how confident are you in that measurement?).
OP
OP
red96jeep
Well-Known Member
I am very confident in all of my measurements, this system has been benchmarked and brewed on enough times now that i feel they are all correct. Also all samples were taken after the wort/beer had been cooled to room temps. I added the liquid beet sugar at the 15 min mark during the boil. why exactly would this actually bring my gravity down?
OP
OP
red96jeep
Well-Known Member
are you referring to my pre boil sample? if so, evaporation is a non issue because the wort is only heated to 170* F so no evaporation would be taking place.
Water and wort will evaporate at room temp depending on relative humidity of the surrounding air. If you're leaving your 170 degree sample out in an open container for 15 minutes to cool your getting evaporation which will increase the SG of the sample. You'd have to evaporate a lot to make a big increase in gravity but it's one possible factor. Try covering your preboil sample with Saran wrap while it cools to keep all the liquid in.
Edit: damn you autocorrect
Edit: damn you autocorrect
Because you're adding a 1.033 gravity liquid to a liquid with greater than 1.033 gravity.
Edit: OK kids, here's where we learn about reading comprehension. OP didn't add a 1.033 SG liquid to his wort, he added a liquid measured at at 1.033 ppg (adding roughly what your typical LME adds to a gallon of water). Disregard the above statement.
