Another stalled fermentation question

[Jaeger]

before anyone jumps me for not searching through the forums for one of the many answers to a stalled ferm question, let me explain.

2 beers with 2 different yeasts seem to have stalled at about the exact same point.

now that i have your attention...

Beer #1
Pilsner, brewed 12/23/19, O.G. 1.059, used Saflager German Lager yeast (2 packets)
Fermented at 50 degrees for about 14 days, raised temp to 60 over 3 days for diacytl rest for 3 days. went to check gravity and taste before beginning the cold crash and, while it tastes good (probably the best I've brewed so far), the gravity was at 1.032 on my refractometer.

Beer #2
Roggenbier, Brewed 12/29/19, O.G. 1.056, used White Labs San Diego Super Yeast (2 packets)
Fermented at 65 for 14 days. Beer fell clear, almost shockingly clear, and tastes good. checked gravity when racking to secondary before cold crashing (in the same chamber as Beer#1) and this one was 1.028 on the refractometer.

I know the refractometer is calibrated. I checked it before use. I have no idea what could have caused two different types of beer fermented in two different areas of the house to stall at nearly the same point. First thought that crosses my mind is that I'll have to repitch fresh yeast which isn't a big deal, aside from having to go and get it. (Morebeer is about an hour away and the closest LHBS to me)

If anyone has any sage advise or has experienced something similar, id love to get these beers at least most of the way to the finish line. Honestly, i was expecting the pils (being a lager) to take a bit longer but I had expected the roggenbier to be done by now.

Thanks in advance
~Andrew

 

[bucketnative]

Don't use a refractometer for gravity measurements once fermentation is underway. The presence of alcohol causes artificially high readings. The refractometer assumes you have water and sugar as the sole actors on the refractive index of the solution. The alcohol throws off the refractive index of the liquid. They were originally intended to be used to measure fruit juices in the field where small sample sizes and fast readouts are required.

There are online converters to allow you to fudge a gravity measurement from the refractometer, but it's best to use a hydrometer when alcohol is present.

https://www.brewersfriend.com/refractometer-calculator/

 

[Steveruch]

Refractometers don't read accurately once there's alcohol and you need to do some calculations to get the correct f g.

 

[Jaeger]

Hahahaha

Of course something so simple would be the answer. Thanks guys, guess I need to order a hydrometer. Mine broke, as they do.

Thanks guys!

 

[RM-MN]

Hahahaha

Of course something so simple would be the answer. Thanks guys, guess I need to order a hydrometer. Mine broke, as they do.

Thanks guys!

Order 2. They are cheap enough and if you have only one it gets lonesome and depressed and will finally commit suicide. With companionship they will live forever.

 

[Harleybrew32]

here is a calculator for converting, but still get a hydrometer
https://www.brewersfriend.com/refractometer-calculator/
cheers

whoops didnt see the earlier post of the calculator

 

[Jaeger]

thanks for the help guys, after adjusting for operator error, here is the final results are:

Pils:
O.G. 1.059
F.G. 1.016
5.7% ABV

Roggenbier:
O.G. 1.056
F.G. 1.012
5.8% ABV

Now I know that i can't use a refractometer for final gravity I've ordered 2 hydrometers and written myself a note on my brewing whiteboard. thanks for the swift replies folks. i will double check my calculations against a proper hydrometer when it gets here tomorrow.

 

[Harleybrew32]

love my refractometer for brewday, but after that its back to the glass