Fermenting: Odd behavior?

I am getting back into this after a long time and have made seven batches in the last few months.

Using Papazian (1991 ed), I made Toad Spit Stout following the recipe except 0.7 less pounds of malt extract and 1/4 pound more crystal malt. According to Papazian, the ending gravity should be 1015 - 1019. Soon (12 hr) after pitching the yeast into a large (7 gallon?) plastic fermenting bucket, fermentation was violent with foam coming out the airlock. This has not happened in any of my recent batches. I replaced the airlock after a couple of days total time, and it happened again, although much less radically. After four days total fermentation time, nothing - the water in the airlock did not budge. I depressed the lid of the fermenter and could make it bubble, but it went right back to level.

Today, after eight days in the plastic fermenter, I racked it to a glass carboy. The SG was 1013 and within minutes the airlock is bubbling at a rate that I would expect for an eight day old fermentation. It tastes fine.

Any thoughts on what's up? I am not so much worried as curious. Perhaps it's simply the natural variation in a natural system?

Thank you,

Jeff

sounds about normal to me


what do you think is odd about it?

Are you saying that in the primary the airlock had stopped activity, and now in the secondary you have alot of airlock activity?

My first question is that it appeared to stop completely after only a few days. I thought that activity would gradually decrease to the point that, even 14 days later, there would be minor activity.

My second question is its re-starting after I put it in the secondary.

Thanks,

Jeff

You roused the yeast when you transferred and they are doing some more work. I've had this happen, totally normal.

Also, airlock activity can be deceiving to actual fermenation. The best answer to is fermentation complete is the hydro readings...

JBC said:

My first question is that it appeared to stop completely after only a few days. I thought that activity would gradually decrease to the point that, even 14 days later, there would be minor activity.

My second question is its re-starting after I put it in the secondary.

Thanks,

Jeff

Click to expand...

Fermentations often appear stop completely after only a few days. The main event is over, but the yeast are still fermenting the last few gravity points and cleaning up by-products from fermentation (e.g., diacetyl).

The physical act of racking to secondary causes some CO2 to be released from solution which in turn makes the air lock bubble. I'd be surprised if it continued to bubble for very long.

Airlock activity is not a good indicator of fermentation activity. I've noticed that airlocks can bubble when the atmospheric pressure changes due to storms or fronts passing through. A hydrometer is the only way to know for sure if you're at or near your target final gravity.

EDIT: Ooops, I re-read the original post and I see you're not really a noob. You probably know everything I just said.

I have had some VERY fast ferments where the yeast were done in less than one day, although these cases were usually pitching on an old yeast cake.... Other than that, +1 on what everyone else has said. You probably just roused the yeast a little + released some CO2 while racking. If your fermentation temperatures are a little high this may also lead to a quicker than usual fermentation.

Thanks very much for al the responses, it really is nice to know that there is a knowledgeable group willing to answer questions.

Jeff

Any time!!!