Help - Keep missing my FG

[kevinb]

Seems like every batch my FG ends up about .002 - .004 higher than calculated. Any suggestions on what I might be doing wrong? This last batch, I even ramped the temp up at the end of fermentation.

 

[Randy_Bugger]

Are you pitching enough yeast?

Are you oxygenating before pitching?

 

[kevinb]

Last batch was 1.050 OG, so I pitched one packet of Wyeast. I don't have any special oxygenation equipment so I am stuck with the shake the crap out of it technique.

I have been brewing partial mash kits.

 

[duboman]

Last batch was 1.050 OG, so I pitched one packet of Wyeast. I don't have any special oxygenation equipment so I am stuck with the shake the crap out of it technique.

I have been brewing partial mash kits.

What temperature are you mashing your grains and is your thermometer calibrated. Personally .002/.004 is not really a huge miss but if you are mashing higher than you think then that will explain a lot.

Also, final gravity estimates are nothing more than estimates based upon certain calculations. If your yeast have performed within the range of predicted attenuation and the beer fully ferments that's what is important

 

[BigJay13]

You should also make sure your hydrometer is calibrated. Mine was off by .006 once.

 

[duboman]

You should also make sure your hydrometer is calibrated. Mine was off by .006 once.

+1
Nice add!

 

[kevinb]

Thanks. Good points on both.

Since they are partial mash, their are not many grains, but I do mash about 160°.

I have check my hydormeter. It was off by about .003 so I make a correction in my measurment. My wife bought me a refractometer for my birthday, and that agrees with my hydrometer.

 

[kevinb]

If your yeast have performed within the range of predicted attenuation and the beer fully ferments that's what is important

Interesting point. I know how to tell when fermentation is complete. However, I don't know how to calculate my attenuation. Any help on this would be apprecaited.

 

[GilSwillBasementBrews]

Thanks. Good points on both.

Since they are partial mash, their are not many grains, but I do mash about 160°.

Try mashing closer to 150 that should give you slightly lower FG.

Lower mash temp will give a more fermentable wort with less body.
Higher mash temps will give a more unfermentable wort. Resulting in a higher FG with more body

 

[GilSwillBasementBrews]

Interesting point. I know how to tell when fermentation is complete. However, I don't know how to calculate my attenuation. Any help on this would be apprecaited.

If I recall correctly attenuation is the percentage of available sugars your yeast convert. As an example if your OG was 1.050 and your FG was 1.000 your attenuation would be 100%. If your FG was 1.010 your attenuation would be 80% if 1.015 you'd be at 70% etc etc.

 

[duboman]

Attenuation is:

[(OG-FG)/(OG-1)] *100=%

Definitely lower your mash temp and you will probably fix your problem, 160 is just too high!

 

[kevinb]

Based on above, my attenuation is 70%. I used Wyeast 1098 which has an attenuation of 73 to 75%. Is it mash temp that would cause that?

 

[duboman]

Based on above, my attenuation is 70%. I used Wyeast 1098 which has an attenuation of 73 to 75%. Is it mash temp that would cause that?

Could be mash temp, could be proper pitch rate, could be proper aeration, could be the %of less fermentable grains like a lot of crystal malt or any combination of these factors

 

[biestie]

Does 1 packet of Wyeast mean no starter? If so, that + the fact that your aeration isn't ideal would lead me to guess that your issue is with fermentation. 160 is maybe a little high, but with a partial mash beer, I don't think it's a big factor.

 

[kevinb]

Correct, No starter.

 

[kevinb]

Thanks to everyone for their help. I brewed and Altbier today. Target gravity was 1.062 and I hit 1.062.

I used a mash temp of 152°F. That might have made the difference.