• Welcome to the new forum! We upgraded our forum software with a host of new boards, capabilities and features. It is also more secure.
    Jump in and join the conversation! You can learn more about the upgrade and new features here.

Can't get my gravity readings to mesh

J

jdjeff

I brewed an Irish Amber which BeerSmith told me should have an OG of 1.54 (right where the recipe said it would be). I used a refractometer to get a gravity reading from the wort before adding water, then used b.s.'s dilution tool to figure out my OG. 1.53. So far so good. I then added, accidently, 1/2 gallon too much water to the fermenter, and also got less than I should have out of the kettle, which, using the various b.s. calculations, should have put my gravity down to 1.46. I took a refractometer reading of the cooled and mixed wort and it came out to 1.43 (using the b.s. tool).  Again, ok.  When the wort finished fermenting, I degassed the sample, and took a refractometer and hydrometer reading. Using the B.S. tool for determining OG from a hydrometer and refractometer, it gave me a calculated OG of.....1.54. Also, the hydrometer showed a FG of 1.013 (corrected for temperature), and the refractometer (again, using the b.s. tool for fermented wort) showed a FG of 1.008. What gives?  Which OG reading should I trust?
 
There are several possibilities:
 1. Make sure your refractometer is calibrated using the "Calibrate refractometer settings" button.

  2. Be very careful taking hydrometer readings.  For example, using the plastic hydrometer tube that your hydrometer came in can really throw things off.

  3.  Small variations in the refractometer readings can have a significant effect on the measurements.  Some people do take more than one reading.

 4. Make sure you are using the "Fermenting Wort Gravity" calculator to determine your final gravity.  Also make sure you used the original gravity of the wort.

In general I would trust the refractometer - they are typically more accurate than the average hydrometer.

Cheers!
Brad
 
I did calibrate the refractometer, took three hydrometer samples, and use a glass hydrometer tube.  I also adjusted for temperature and used the right calculation.  My real issue is the difference between the calculation of OG using the refractometer + dilution tools at the beginning, and the calculation of OG using refrac. + hydr. at the end.
 
 I'm not really sure what might be wrong here.  I have checked the equations multiple times against multiple sources.

 I would  be more than happy to discuss the calculations in detail if you want to send me an email with your measurements and calibration used.  That way I can check it out here with the debugger on and try to determine if there is some kind of problem.

Thanks!
Brad
 
"Using the B.S. tool for determining OG from a hydrometer and refractometer, it gave me a calculated OG"

Can you post the recipe, and your raw readings (refractometer in Brix)?  Then we can get a better idea of what might be going on.

Fred
 
Back
Top