I planned a 6 gallon sticke alt and decided to split the batches to compare the performance of two yeasts. There were a few interesting things to note.
I used a starter for both yeasts (1 liter) and aerated with pure o2 for a little under a minute. The beers fermented on the low end of the scale in my chest freezer, about 55 degrees. I pitched the 2565 @ 65 degrees and the 1007 at 70
The 1007 took off with an incredibly vigorous fermentation...lots of blow off. The Kolsch yeast as a lot more restrained (again, no hydrometer reading yet so just an observation). There was very little sulfur in either batch and no diacetyl. After 7 days I took a gravity reading and was surprised to see the German ale was stuck at 1.031 (50% attenuation) while the Kolsch yeast had fermented to 1.020 (67% attenuation). I think the only explanation was the cooler temps...Wyeast claims that 1007 works well at 55, but it didn't seem to be fermenting.
Both beers had giant, rocky heads on top.
I ended up raising the temps to 62 in the freezer and the Kolsch finished at 1.01 and the German ale at 1.012.
The German ale flocculates a lot better than the Kolsch yeast. but since I'm lagering this beer at 40 degrees for 30 days I bet once it's ready there won't be any perceptible difference.
Taste wise I prefer the german ale; smooth, clean, malty. The Kolsch gives off a "lead pencil" taste. I've tasted this a few times in other commercial kolsch beers, wonder if anyone else has noticed the same taste?
in any event, Ill probably continue to do split batches, it adds an element of comparison which makes brewing even more interesting...could even dry hop one/ sour one and leave the other alone. its gonna be a busy winter!