airlock not bubbling after 72 hours....

[just_steve]

My second brew started on Sunday. And everything has seemed to gone well until today. I keep the FV in my log cabin as I don't fancy discovering if my cat would like to use it as a warm place to sit on or to use as a plastic scratching post. The only problem with the log cabin is temperature. I have an oil heater out there to stop the log cabin from going below freezing, but over this extended winter I doubt it's managed to get much over 10-12oC. I have an aquarium heater in the FV and the FV feels warm to the touch. Also, there is a sticky thermometer on the outside of the bucket which reads 20oC. So far so good. The thing that's concerning me is that the airlock isn't bubbling (especially as it did quite regularly by this time the last time I did a brew). The strange thing is, however, there's a reasonably sized yeast cake at the bottom of the FV. So the yeast has obviously multiplied to some degree.

What do people think?...

...I think it's an issue of temperature still. Evidently the temperature in the liquid itself is around 20oC but I fear the yeast cake at the bottom is at a lower temperature because it's 'around the edge' so to speak. I also wonder if the temperature in the log cabin has caused the yeast to flocculate too early?

I think I'm going to leave it for another day and see whether I was just being over anxious. If there is still no sign of air bubbles, I'll stir the yeast cake up, add some nutrient, take advantage of opening the top up by taking a sample for a hydrometer reading, and wrap up the FV in a duvet on top of having the aquarium heater set to 20oC.

Any better ideas or does that sound fair?

 

[Stu]

I wouldn't worry about it.

I did a Cider that never bubbled. But it's dropped down to almost 1.00

Thing is, particularly if you've got an aquarium heater in it, it's probably not airlocked. Check the FV all the way round - if it's loose then the air is escaping that way. Look at the plastic bit by the handles and you'll probably be able to see that they don't always seal that well.

It seems to come up here on a regular basis. I worried about it the first time.

 

[marksa222]

I doubt the temperature difference would be too great. If you run a bath, the temperature by the tap isn't much warmer or cooler than the other end for too long. With there being a constant heat source for the FV, I'd imagine the temperature would be fairly consistant throughout.

Are there any other signs of fermentation? A krausen ring for example?

I think if the airlock isn't sealed properly, the co2 can escape without bubbling up.

 

[dennisdk2000]

Take a gravity reading - if the beer has reached a reasonable level of attenuation (depending on yeast strain and recipe), it has simply fermented a little faster than you expected - 72 hours is enough for a beer to attenuate fully. However, it might still be beneficial to leave the beer on the yeast for a little longer, or you may get too much diacetyl character. You could do a forced ferment test: remove enough beer to take a gravity reading and then some. Cover the sample loosely with foil and place at 27°C. If you see any activity, your beer hasn't reached maximum attenuation, but then most beers don't. If you don't see any activity, take a gravity reading after a couple of days; otherwise, take the gravity reading once activity has stopped. This is the lowest possible gravity for that particular beer. If the reading from your FV is close, the beer is done - if it's quite a bit off, rouse the yeast and keep an eye on the temperature to make sure it stays in the desired range.
You can do a forced ferment test on each beer you brew: as soon as you've pitched the yeast, draw off a sample and proceed as above. It takes some of the guess work out of proceedings! Also, I highly recommend reading Yeast by C White and J Zainasheff!

Dennis