Help Me Understand Attenuation

[jklotz]

I've got a nut brown ale in secondary. It's been in primary for 10 days, secondary for 14. Trying to decide if it's ready to keg. The OG was 1.062, and it's now at 1.017. The yeast was an English Ale Yeast WLP002, which quotes an attenuation rate of 63-70%. Being a complete moron at math, what's my attenuation rate? Is it ready? It seems to be holding steady at 1.017 over the last few days, but I'm getting a bubble in the airlock every couple of minutes. What do you think?

 

[The Pol]

OG-FG then divide that by the OG. Example:

62-17 = 45
45/62 = 72.5% attenuation

EDIT: regardless, if there is bubbling in the airlock, I would NOT bottle it.

 

[jklotz]

Thanks Pol. So judging by that, it would appear that, despite seeing a bubble in the airlock every 2 mins or so, it should be ready to go. Would you agree?

 

[brewt00l]

62-17= 45
45/62 = 72.6%

Edit: Doh beat!

If it's reading the identical 1.017 over several days, you should be ready to roll

 

[The Pol]

My concern is that if it is still giving up CO2... and you bottle it, there is a possiblity, for whatever reason, that pressure could build up in the bottles. Seems odd to have that much attenuation and see any bubbles at all in the airlock.

EDIT, you are kegging it, go ahead and keg it, no problem! Bottles scare me!

 

[Edcculus]

If your gravity is stable, its just out gassing CO2. Use Beersmith to caluclate how much priming sugar to use based on the temperature of your beer. It takes into account residual CO2.

Brew Strong (Jamil and Palmer) has a great podcast on attenuation.

 

[rico567]

EDIT, you are kegging it, go ahead and keg it, no problem! Bottles scare me!

If I am careful not to bottle before I achieve FG -or within a few points of it- and don't over-prime, bottles don't scare me at all.

 

[The Pol]

Are You Kidding Bottles Are Dangerous!!