Question: How long / what temp should I do a diacetyl rest for my kolsch? Detail: have a kolsch that I just brewed Monday night (7/14). Pitched a single vial of wlp-029 into 1L starter wort, let let ride on a stirplate for 20 hours, crashed for a few hours in the fridge while I brewed, decanted, pitched the remaining liquid+slurry into the 3.5 gal kolsch wort (OG 1.052) at 62F. Continued cooling in the ferm chamber and had it at 59F within 2 hours of pitching. stabilized and fermented at 60F. Thursday morning, had zero airlock activity, as in completely dead. Raised temp controller temp to 62F, let the temp rise through this morning (friday, 7/18), when I took a gravity reading of 1.010 (target FG is 1.010). No krausen, but lots of clumpy yeast floating around on top, and the sample I took was pretty cloudy. I'm pretty surprised at how fast the fermentation chewed through the wort (3 days?!?). I plan to drop temps gradually after the d-rest and lager for a week or so before bottling for some conditioning and cold-conditioning to help clear it out a bit more...
I brew a ton of Koelsch, and I have to say I have never seen 029 blow through that quickly. However, the fact that you did a starter for 3.5 gallons may explain that result. The lack of Krausen kinda gives me pause, too. Got any pics? As for the d-rest, I'd agree that bumping it to around 65-68 and then tasting is the way to go.
So it fermented in a bucket, so I don't have a bunch of visuals, but I did open it briefly on Wednesday morning and it had substantial krausen. When I opened it this morning, just a dozen or so dime-sized clumps of yeast floating on top and the liquid was quite cloudy with yeast. As to fermentation speed, the only thing I did differently than normal was with the water. I usually use walmart or kroger (fry's here in az) brand drinking water in 1 gal jugs. This time, I ran my phoenix tap water through a brita filter and used that for both the starter and the brewing water (no yeast nutrient or other adjustments). Here's the latest report I got on my treatment plant's water profile as of January: alkalinity 125 mg/l calcium 71.8 mg/l magnesium 28.4 mg/l sulfate 211 mg/l chloride 83.5 mg/l sodium 79.6 mg/l Is it possible that water could make the difference? Gotcha, 65-68F for the d-rest. Thanks!
