[Wilbur]

So, I brewed a pilsner, and was trying out my new fermentation chamber. Quick breakdown of the situation:

• Brewed 5 gallons, split into two fermenters (3.5 gallon brewbuckets)
  • Fermented 2.5 gallons cold (14.4 C (58F), short ~1 day diacetyl rest at 18.3C (65F)). Cold crashed & gelatin fined
  • Fermented 2.5 gallons at room temperature (72 F), cold crashed and gelatin fined
  
  I have a definite diacetyl/ butterscotch taste to the cold fermented beer, I tried letting it rest at  room temperature for a few days to see if it could clean up. No such luck. Any tips on how to fix this? I was thinking about throwing some yeast and a bit of DME or sugar in, but I wasn't sure if there was anything easier.

[denny]

So, I brewed a pilsner, and was trying out my new fermentation chamber. Quick breakdown of the situation:

• Brewed 5 gallons, split into two fermenters (3.5 gallon brewbuckets)
  • Fermented 2.5 gallons cold (14.4 C (58F), short ~1 day diacetyl rest at 18.3C (65F)). Cold crashed & gelatin fined
  • Fermented 2.5 gallons at room temperature (72 F), cold crashed and gelatin fined
  
  I have a definite diacetyl/ butterscotch taste to the cold fermented beer, I tried letting it rest at  room temperature for a few days to see if it could clean up. No such luck. Any tips on how to fix this? I was thinking about throwing some yeast and a bit of DME or sugar in, but I wasn't sure if there was anything easier.

You're on the right track.  You want to krausen the beer.  That involves adding about a qt of actively fermenting wort.