..a filter was my first idea. I'm thinking I need to step back and ask exactly what your question is? Yeast rafts are common enough.. I usually use some kind of screen or filter when transferring to make sure they stay out. I'm likely misunderstanding what it is you're asking.
When I make Cinook IPA in an All Grain with either S04 or S05, for some reason I get the same thing happening. With certain yeasts strains, under some conditions, I have found that these yeast clumps remain after my fermentation is completed and verified through my gravity readings. I ignore it because all ale yeasts are top fermenters and on occaision some of the yeast may remian visible on top of the beer. I am going to try Cali dry yeast next time to see if this works better.
I do the same. Both last time and this one I tasted the beer and both times is tastes sour with none of the traditional grapefruit after taste. If it's an infection of two of the same beer, that has never happened to me, and it would be the first time in 35 years. This is why I am switching to a diffrent yeast. I terms of a soured beer, it came out great!
