Over Shooting Final Gravity

[Tuckerl]

So I need a little help. Over my last two batches, I have been overshooting my final gravity by quite a bit. I've been hitting my OG right on but have blown past my expected final gravity.

One example had an expected OG of 1.107 (I was a little under at 1.104) and an expected FG of 1.023 with the actual FG ending at 1.011. The beer itself needs some time to sit I think but in tasting it all I get is hot alcohol.

Any suggestions as to what could be causing me to over shoot my FG's?

Thanks!
Lee

 

[BryceL]

The first question is are you brewing all grain and what are you using to predict your gravities? Beersmith or other program? If your using a program and are brewing all grain, my first thought would be that you might be missing your mash temps (too low). If this is the case make sure your thermometer is celebrated.

 

[Tuckerl]

Thanks for the response. I brew all-grain via BIAB and my thermometer is good. I use Brewer's Friend and BeerSmith for my recipes.
The recipe I referenced called for 90min at 152 & I kept pretty close to that. Yeast was WLP540 Abbey Ale.

 

[BryceL]

White Labs states 74-82% for that yeast. Have you calibrated your hydrometer or refractometer, temperature corrections, etc.? If your gravity readings are correct, you are getting 90% attenuation. That beer will definitely need to mellow for a while!

 

[duboman]

It sounds as though you are mashing lower than you think and that means the thermometer you say is good is actually off

 

[biodarwin]

Assuming your thermometer / hydrometer is correct, mash for a short period of time. This will help control your attenuation.

Reference: https://www.homebrewtalk.com/f36/controlling-attenuation-through-mash-times-60576/

 

[Tuckerl]

Well now I don't know what to do. I tested my thermometer against two others at various temps and it was within one degree of the others. Also, I kegged two other brews last night and they both went past their estimated FG. Now what?

 

[Flask]

What were your recipes and your mash schedule for the last three batches? Sounds like a tripel/quad for the first one you mentioned. Also what were the OG/FG of the last two batches?

Flask

 

[nukebrewer]

Well now I don't know what to do. I tested my thermometer against two others at various temps and it was within one degree of the others. Also, I kegged two other brews last night and they both went past their estimated FG. Now what?

What temperatures did you test it at? If the other thermometers were also off, then using those as your known values wouldn't do much good. The easiest way to calibrate a thermometer is to make sure it reads 32 F (0 C) in ice water and 212 F (100 C) in boiling water. Given those two calibration points, you should be good in that range (in theory).

 

[biggmatt]

If the primary fermentation temp is too high, yeast will produce more alcohol faster. You can get fusel oils. Fusel oils are complex alcohols like galactose is a complex sugar. They taste like hot alcohol. It will take some time for them to break down. May never go away.

 

[Qhrumphf]

What temperatures did you test it at? If the other thermometers were also off, then using those as your known values wouldn't do much good. The easiest way to calibrate a thermometer is to make sure it reads 32 F (0 C) in ice water and 212 F (100 C) in boiling water. Given those two calibration points, you should be good in that range (in theory).

What he said.

I had this exact same problem. I was using three thermometers, all if which ready +/- 1°F of each other. Then I found out they were all reading 3 degrees too high. I adjust now, and my attenuation is back where it should be.

 

[daksin]

Software is notoriously bad at predicting FG. It looks at the yeast's average attenuation range and just takes a percentage of your OG. It's nothing more than a (poorly) educated guess. Most yeasts I work with dry out farther than advertised; personally I would just ignore whatever your predicted FG is and learn how the yeast behaves in your hands, then use ingredients and mash temperatures to adjust the attenuation.