Hydrometer vs Ebulliometer Results

Hi everyone,

I have been fermenting a fruit wine for a couple of months now as an assessment piece, however I have run into a conundrum with some testing results. I first started out with a must that I called a 'control' and then split that control into three separate fermenters. One fermenter was not altered, the other two were altered so that pH was increased and decreased. Overall, the average pH over the fermentation was:

1. Control = 3.6
2. Increased pH = 4.40
3. Decreased pH = 3.10

Throughout the fermentation period hydrometer readings were performed. Towards the end of fermentation the hydrometer reading for the control was 0.992, the increased was 0.900 and the decreased was 0.980. However the ebulliometer readings at the end were control = 13.2% alcohol, increased pH = 13.2% and decreased pH = 12%. From my knowledge the hydrometer and ebulliometer results do not allign, any ideas as to why?

Could the hydrometer results compared to the ebulliometer results be due to the differing amounts of sugar in each fermenter to begin with?

Jordhard said:

Towards the end of fermentation the hydrometer reading for the control was 0.992, the increased was 0.900 and the decreased was 0.980.

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These figures are almost certainly in error. A SG of 0.900 is incredibly low, basically impossible to get to via fermentation. Even 0.980, while perhaps achievable by fermentation in principle, is never seen in practice.

Here is a good video on how to read a hydrometer:
[ame="https://www.youtube.com/watch?v=ty7PAJaBsts"]https://www.youtube.com/watch?v=ty7PAJaBsts[/ame]

Jordhard said:

I first started out with a must that I called a 'control' and then split that control into three separate fermenters.

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Jordhard said:

Could the hydrometer results compared to the ebulliometer results be due to the differing amounts of sugar in each fermenter to begin with?

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These statements seem to be in contradiction. Why would the amount of sugar differ if you split up a single batch?

sour_grapes said:

These statements seem to be in contradiction. Why would the amount of sugar differ if you split up a single batch?

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Thank you for clearing up the hydrometer readings, I fixed up the readings to assume that they were 0.990 (instead of 0.900) as well as 0.998 (instead of 0.980 and they are far more reasonable (coincide with the alcohol content from the ebulliometer too). As for the differing amounts of sugar, I was theoretically wondering if there was undissolved sugar at the bottom of the initial control must that would transfer unevenly into the fermenters. However this question was more for explaining why I recorded the near impossible readings on the hydrometer.

When you used the ebuliometer, how far apart were the tests? Did you recalibrate (boil water each time just before testing? If several hours went by the barometric pressure could have changed in the room causing different readings.
I keep a digital barometer in the lab. If it changes after my first test, I redo the first part of boiling water over again before testing the next wine.
Remember the Ebuliometer is about as accurate as you're going to get but the TTB still gives you a +- of 1.5%.