My last 2 batches of beer have both had a small amount of the yeast remaining on the top of the beer, floating, while 95% of the rest of the yeast (ale) had flocculated. I have been brewing for 2 years, and have never had this issue before. First, the facts: These batches were 2 different extract styles, Gluten free (sorghum based) and Oatmeal Stout. Both batches used different yeast, Wyeast, high floc (smack pack) and White Labs, med floc (starter used). These batches were brewed one week apart from each other in 2 different pails (same style, different physical pails) I aerate very strong, with a drill and a stir stick, in addition to a lot of 'splash' with my filtering method. The medium flocculation yeast fermented for 16 days and the high for 9. Both of them reached their expected/calculated F.G. Both batches remained in their temp. ranges for the entire time, and for the final 3 days I dropped them both down to about 63 degrees to try to promote more flocculation.

Now, my speculation: The one thing that both of these had in common is that they both reached the bottom of the pail, even blowing out the air lock (and eventually just the hole as I had to remove the air lock), during the fermentation. I have about a 4-5 inch headspace on these pails. While racking these beers, I noticed that it almost seemed to be that the yeast was being held a float by numerous bubbles trapped in the yeast foam. In the course of taking my gravity reading and some last minute sanitizing, I noticed that the yeast in the first batch nearly completely 'sunk' by the time I got it ready to rack. So in the second batch (the following week) I intentionally went in and tried to pop as many of these bubbles as I could. In so doing, it was very apparent that the yeast was in a flocculant state as the slurry was quite glutenous (like when making bread), and that if given a few more minutes it would have probably sunk. It was much quicker for me to just skim off the yeast at that time and get going on the racking, which I was more comfortable doing given my increased chances of contamination at this point.

So has anyone seen this before? Do you know of a way to insure that the Krausen does not reach the bottom of the pail lid? Should I change over to carboys with blow off tubes and just let it go? (don't prefer that due to the loss of lupulin oils) Should I just make slightly smaller batches? Is there a root cause to this issue that I am missing?

Any help or insights would be greatly appreciated. Cheers!