A question/problem about gravity calculation

[ozgu]

Hello everyone, this is my first post. But i was also a follower of homebrewtalk before my sign up. So, i made my first beer on 20th of September. I used biab method, and my recipe was as following:
*2.55 kg German Pale Ale
*0.5 kg Munich 1 (light)
*0.25 kg Melonoidin
*0.325 kg Cane sugar
*19 liter strike water
*~15,5 liter Pre boil (with sparge)
*~12,5 liter Pre fermentation
*T-58 yeast

Pre boil gravity was 1,058, and O.G. was about 1,075. Then, i measured 1,013 S.G. two days ago, at 2nd week of fermentation. (All gravity values corrected for temp.)
So, my problem is, according to Brewer's Friend's OG/FG calculator, F.G. should be 1,020. And the yeast that i used, has medium attenuation. But, look like that my F.G. value will way more low, and according to calculations, abv will be between 8-9%.
Am i doing something wrong, or everything is normal ?

Thank you.

 

[Smellyglove]

Hello everyone, this is my first post. But i was also a follower of homebrewtalk before my sign up. So, i made my first beer on 20th of September. I used biab method, and my recipe was as following:
*2.55 kg German Pale Ale
*0.5 kg Munich 1 (light)
*0.25 kg Melonoidin
*0.325 kg Cane sugar
*19 liter strike water
*~15,5 liter Pre boil (with sparge)
*~12,5 liter Pre fermentation
*T-58 yeast

Pre boil gravity was 1,058, and O.G. was about 1,075. Then, i measured 1,013 S.G. two days ago, at 2nd week of fermentation. (All gravity values corrected for temp.)
So, my problem is, according to Brewer's Friend's OG/FG calculator, F.G. should be 1,020. And the yeast that i used, has medium attenuation. But, look like that my F.G. value will way more low, and according to calculations, abv will be between 8-9%.
Am i doing something wrong, or everything is normal ?

Thank you.

A software calculator is as you said, just a calculation. Never trust an FG "estimate" from a calculator. It does not know the factors in your setup. The only good ballpark is your own experience.

 

[ncbrewer]

A software calculator is as you said, just a calculation. Never trust an FG "estimate" from a calculator. It does not know the factors in your setup. The only good ballpark is your own experience.

+1 As long as you've checked the calibration on the hydrometer, that's what you should believe. If you were to get an especially low FG, you might be worried about infection, but yours seems reasonable - although I've never used T-58 yeast.

Welcome to HBT.

 

[ozgu]

Thank you for replies. Today, i measured the gravity, and it was about 1,012 with corrected temp. So, after 1 week there was not much gravity change, but also i observed that there is still slow and weak co2 out on surface of the beer and it became more clear and dark. So, should i start bottling ?
Thank you.

 

[ncbrewer]

Many would disagree, but I would wait three days and check again. It gravity is exactly the same, it's ready. I tend to be very conservative when it comes to safety.

 

[ozgu]

Many would disagree, but I would wait three days and check again. It gravity is exactly the same, it's ready. I tend to be very conservative when it comes to safety.

Thank you for your help. As i wrote, my main concern is, beer still give off co2/gas without bubble, and when i checked shortly before it was still continue. So, because of this i can not be sure about bottling. But also, it look like that current attenuation is about 83-84% according to 1,012 gravity. If we consider the yeast that i use has medium attenuation, beer should be done.

 

[RM-MN]

Your fermented beer will continue to slowly give off bubbles for weeks after it is ready to bottle. During fermentation much more CO2 is dissolved into the beer than it can hold long term and it will keep coming out of solution. Your hydrometer is the right tool to tell you if your beer is ready to bottle. A steady reading near the expected FG for a couple days and you can bottle.

Many would disagree, but I would wait three days and check again. It gravity is exactly the same, it's ready. I tend to be very conservative when it comes to safety.

I agree with Ncbrewer that identical readings 3 days apart tells you it is ready to bottle but I also agree that he/she is being very conservative.