Completion Of Fermentation

[jason]

Hi

Could someone tell me when it would be safe to bottle my brew. On 7/706 i did my first AG. I started out with 4.5Kg of pale malt(JW) and 0.5Kg of crystal malt (JW) and could only manage to get about 13L following boiling (the final volume was small due to a stuck sparge and incorrect calculations, it was my first AG'er). When I used the hydrometer to obtain the first SG I used the wort that was left behind in the boiler because i didnt want to use the wort that was already in the fermenter as I had so little of it that i didnt want to waste it. So as you could inmagine, my SG of 1.086 is only an estimate as the trub could have affected the way the hydometer floated. I recently got beer smith and plugged in my brew and was suprised to find that beersmith estimated the SG to be 1.088 which is very close to what i obtained. Beersmith also estimated that my final SG should be approximately 1.022. Tonight 14/7/06 I decided to take a reading (and also to have a taste, and it was nice) and got a SG of 1.020. So is it safe to bottle my brew?? Ive heard that wort that has been bottled without fullly fermenting out may cause the bottles to explode. I should also mention that the temperature of the fermenter has not been ideal for the first couple of days of fermentation as it has been quite cold here in sydney in the nites. The airlock doesnt really bubble until i supply some external heat such as the heater. The fact that when I supply some heat the fermenter begins to bubble (very slowly at this stage) does this mean that fermentation is not complete and I should not bottle my brew eventhough beersmith states that it is completed. (the fermenter now sleeps in my room as ive got the heater going most of the time... folks think ive lost it )

Thanks.
J

 

[goatherder]

it sounds like you have got a reasonably complete ferment - 1.086 down to 1.020 is 76% apparent attenuation. It depends on what sort of beer and what sort of yeast you are using. Post some more details and you might get some better info back.

The thing that strikes me is that you've only had it fermenting for a week. Leave it for 2. Especially if you've still got bubbles.

Even though you've had an excellent drop in your SG, the yeast won't be finished. They ferment all the easy stuff first and create a bunch of intermediate by-products while they are doing it, like diacetyl. They tend to clean this stuff up later in the fermentation. You might only get a few more points drop in your SG, but you'll get a much better beer for it.

Good luck, it sounds like you are going to get a mighty tasty beer for your first AG.

 

[kungy]

Hi Jason,

Just a couple of points.

When you apply heat to it CO2 is coming out of your beer. Generally the higher the temp, the more gas will come out of the solution. So the yeast may not be producing CO2, but the CO2 that has already been produced is just coming out.

The rule of thumb is ignore the airlock and rely upon the hydrometer. Its an invaluable tool. Two days of the same reading at a FG that makes sense is a good measure as to completeness (ie ok to bottle) when other variables make sense ie yeast is actually alive, beer at the right temp for the yeast etc.

As Goatherder said give it more time in the fermenter. Its tough to do sometimes, but is a good step that can aid the beers taste and help ensure its completeness.

According to the science in my head, the trub at normal levels shouldn't affect the hydrometer readings (feel free to correct me otherwise) as the reading is only of the liquid, trub, cold break and all.

Definately post some more info if you can. Yeast type would be most helpful

Will

 

[jason]

Sorry i forgot to mention that I was using dried yeast (Safale s-04, all 11.5grams of it), if that helps with your comments. I wasnt trying to make any beer inparticular. So is 2weeks the normal time frame to keep it in the fermenter before bottling?

Cheers,
J

 

[NRB]

So is 2weeks the normal time frame to keep it in the fermenter before bottling?

For me, absolute minimum.

On a side note, what size batch were you shooting for? If it was significantly more than 13L with an OG much less than you achieved, you may want to consider watering it down with boiled/distilled water prior to bottling. It would be a shame to tip your first AG due to being a beer that is too strong/bitter.