On Nov. 11, I brewed an Irish Red Ale (Donovan's Irish Sunset). The yeast was a washed Wyeast Irish Ale that had been used just once before, in a Dry Irish Stout. The yeast had spent barely a day in storage (in the fridge) before being pitched into the Irish Red Ale.
I fermented in a 6.5 gallon carboy, sitting in a plastic rope tub filled with water, replacing 2-3 frozen Gatorade bottles twice per day (morning & night). The carboy was covered with a wet t-shirt.
After a week (Nov. 18), I moved the carboy out of the swamp cooler and up onto a shelf, where it's been sitting ever since. The temperature strip on the carboy indicates 66-68 F.
I took a gravity reading 2 weeks ago, and it came in at 1.010, so I think it's done. But here's the weird part - the airlock is still bubbling.
I know, I know, "the airlock is not a sign of fermentation, lots of things can cause it to bubble." But the thing is, I can't imagine what else it would be. The carboy has not been touched or disturbed, so it can't be gas being knocked out of solution. The temperature hasn't changed, so it can't be expansion/contraction of air in the carboy. And there are several small "islands" of clusters of bubbles on the surface of the beer. When I watch the airlock, it's not like it's frequently bubbling, but there are bubbles in the StarSan in the airlock, indicating that there has been activity. And the beer is pretty cloudy, suggesting there is still convective activity inside preventing sediment from settling out.
I was hoping to cold-crash, gelatin, and keg this thing over the next week. And the gravity suggests it's done. But these other signs are making me apprehensive. Has anyone else ever experienced anything like this? Any suggestions as to what might be going on? Is it the washed and reused yeast that maybe just doesn't want to quit?