Beersmith 3 FG calculations problem

Hello,

That's my first post so please be patient

I have problem with Beersmith 3, i think... My first beer, after upgrading BS, was Old Ale and everything went just fine. Problem started yesterday when i finished my scecond batch - Session APA.
To the point, Iam using refractometer, after boil it showed 8,5 Brix, after fermenting almost 2 weeks the measurement was 2,9 Brix. When i entered numbers into Session tab it showed 0.077 Brix in the Final BLG/FG column. How is this possible?!

Thanks a lot for all your replies.
Cheers!
Luk     

Your experience us not uncommon.  The calibration of your refractometer is for sugar in water.  As soon as the wort starts fermenting and there is alcohol present, the calibration no longer is accurate.  There is a correction factor for this offset caused by the alcohol.

You can use the refractometer tool in BeerSmith and set the type to fermenting wort.  You will need to enter the og reasing and your brox reading on the fermented wort.  The program will give you the corrected fg reading.

Even better yet, you can access this tool from the sessions tab in your recipe.

Thats why i am writing.
Ok, maybe I was not accurate, I will try again.
I made beer, Before pitching yeasts:
8,5 Brix -into program-> 8,29 BLG (1.033)
After fermentation:
3,2 Brix -program-> 0,077 BLG (1.000)

Refractometer tool in BS showed 1.000 FG, that?s why I am asking is it possible that yeasts ate almost all the sugars ?!

More like my interpretation of your original message.  I was away from my computer and it is hard on old eyes to read the forum on my cell phone.

Getting to your issue, what type of yeast did you use?  Was the recipe mostly extract, all grain, grain with simple sugars? 

There are a few possible explanations for your low FG reading.  First, could the calibration of your refractometer.  Next, depending upon the yeast strain used and a good percentage of sugar in the recipe, you can attenuate down that low.  Lastly (and sadly), you may need to consider contamination by wild yeasts or bacteria which will eat away not only at the maltose in the wort but further eat away at maltotriose the more complex dextrins in the wort.  This may or may not be apparent in the taste of the finished beer, depending upon the type of contamination.

Firstly I want to thank you for replying so fast and with such a good attitude.
Secondly:
1. It is Session Ale
2. All grain, English Maris Otter 100%
3. Yeasts US-05 (dry but hydrated)
4. Refractometer is calibrated before every batch with distilled water
5. All others measurements in BS are correct.
6. I hope it is not contamination:/