Opening lid starts stuck fermentation?

[tenchu_11]

My beer started out with a perfect fermentation. Within 5 hours pitching the yeast the air lock went crazy for about a day and a half or so then. Then for the next 4 days the 3 piece air lock just laid in place not even floating. I know it was a bit odd since most beers i've brewed before would at least float showing a mild production of Co2. I opened the bucket and noticed the Krausen had yet to sink, i used my hydrometer to lightly pushed it apart like the red sea and took a quick gravity reading. It had started out at 1.043 and it was at 1.023, only about a 2% alcohol beer...kinda lame. So I closed the lid and left it as it had been and went to sleep. For the last 2 1/2 days my air lock has been going crazy, my theory is that opening the lid helped kick start the fermentation again. Although It could mean some contaminate is the thing that helped. My brew is homebrewers out post American Hefenweizen with White Labs American Wheat yeast. It has been fermenting at around 68-73F. I know air lock activity isn't an indication of fermentation but it sure is encouraging to see.

 

[kwhyte]

I think it's more likely the lid wasn't quite airtight so the co2 was escaping without visible airlock activity but when you closed it you sealed it so the activity was visible in the airlock again.

 

[LagerLover24]

I can't think of any reason it would restart fermentation. I agree with kwhyte on this one. This is one of the reasons I like glass carboys. Being able to see the fermentation gives me peace of mind.

 

[rsavage]

I just had literally the same experience with an extract batch of Irish Red we just brewed. The beer had been in primary for 3 days and stopped bubbling after about 2 days of vigorous fermentation at 65 degrees F. I thought maybe it was finished since it seemed to be raging away initially, but when I opened it up today to take a FG reading it read only 1.020, so I sealed it back up and within an hour the airlock was bubbling away again.

I figured exposure to oxygen might restart the yeast, but I see that this might not be the case.