Stuck FG...help me Oprah Winfrey!

[drinkindinkins]

I brewed a porter about two weeks ago. The OG was 1.040. It should've been 1.046 (I'm still working on figuring out the efficiency of my brew system, topic for a different time). The Last gravity reading I took yesterday was 1.024. I used a stir plate. 1200mL of wort for a few days.

First question: this was taken with a refractometer. I just got this fancy thing but I know you have to use a calculation or converting tool to get the correct gravity reading. Can someone offer up a link or something for it?

Second question: I think the yeast might not have been as active as I thought. To lower the gravity can I add another packet of yeast and/or add some sugar to give it some more food to munch on?

 

[kaconga]

http://www.northernbrewer.com/refractometer-calculator/

That link says the actual FG is 1.014. So that doesn't seem stuck at all unless there is extenuating circumstances.

 

[drinkindinkins]

Could you explain how to use that? I used the second box typed in my original and final brix measurement and it gave me a measured gravity of 1.005. Does that mean that is the measured current gravity? Thus meaning my beer is 4.5%?

 

[Yooper]

Could you explain how to use that? I used the second box typed in my original and final brix measurement and it gave me a measured gravity of 1.005. Does that mean that is the measured current gravity? Thus meaning my beer is 4.5%?

Refractometers aren't accurate once fermentation takes place as alcohol skews the refraction of light. There are calculators out there, but I've never found one that is accurate. The best one I found is this one: http://seanterrill.com/2012/01/06/refractometer-calculator/ but it's not entirely accurate either, unless you know your wort correction factor.

here's some great info (from the same site) on why this is: http://seanterrill.com/2010/06/11/refractometer-estimates-of-final-gravity/

Check with a hydrometer. Then you'll know for sure, but your beer isn't stuck either way.