Split Lager Batch: One at 47, One at 67

[Asator]

Hello,

On 1/1, I brewed a 5-gallon IPL batch. I used Pilsen Lager Yeast (Wyeast 2007), and used a two stage yeast starter, 2L each time. BeerSmith calculated that I would have 536.8 billion cells after the two starters, and said I needed 548.5. I figured it was close enough.

I split the yeast slurry and batch into two 3-gallon glass carboys. One I fermented at room temperature in my basement, at 67° F. The other I fermented in a wine fridge I set at 47° F.

About a week ago, I pulled the 47° carboy out of the fridge because I noticed a stark color and clarity difference. A week later, there is obviously still a difference. I have not taken gravities on either yet, will be doing that this evening after work. Any initial ideas on the color difference? The one on the left was fermented at 67° and the right was at 47°.

 

[LLBeanJ]

The yeast is going to work faster at the higher temp, so the the one on the left is pretty much done and well onto clearing, which is why it is darker. The one on the right is still fermenting, so lots of stuff in suspension giving the cloudy appearance and lighter color.

Edit to add... I just re-read your post and noticed the 1/1 brew date. The cold fermented one should be done by now and clearing as well, so no idea why it isn't.

 

[Asator]

@LLBeanJ Agreed, that's what I thought too. I'm pretty sure that once I take a gravity on the colder fermented one, it won't be finished. I just didn't know why. And I figured that bringing it up to room temp about a week ago would have given it a little boost to keep working, but the krausen that was on it when in the fridge has pretty much disappeared and it's still cloudy and lighter in color.

I figure it should have been done after 5 weeks also. Maybe stuck? Maybe not enough yeast pitched originally.

 

[LLBeanJ]

Yeah, very weird. Check the gravity on both to see where they're at.

 

[Gnomebrewer]

Do you have a pH meter? It's quite possible that they are different, given the likely difference in fermentation intensity. pH can have a significant effect on colour.