I made a Kolsch with 2565 with an 8 day primary fermentation at 60F, then racked to a secondary for another 7 days at 60F then took it to 45F to get the yeast to floc. The next step is to slowly drop it to 32F. This schedule was recommended by another brewer more experienced with lagers than I.
Anyway, I somehow dumped my first hydro sample when I racked to secondary and didn't sample it again until now (at 45F.) The problem is, I can taste diacetyl. It's not strong, but definitely there and if it remains at this level, it will not be to my liking. I'm certainly more sensitive than some to diacetyl, so again, the levels aren't high, but detectable and I'd rather have them cleaned up a bit.
So, my question is what to do? Is it too late to do a diacetyl rest? I brought the beer back up to 65F last night and the yeast were rousted a bit from me moving the carboy. I didn't want to roust too much because I've been told 2565 is a b**** to floc, and that was the whole point of the crash from 60F to 45F. Should I add some yeast nutrient to get them active again? Or should I have just left it alone?
From what I understand about lager fermentations, the yeast stay active even at lager temps, so should I just drop it slowly to 32F and wait it out? Will it clean up? If so, what's the point of a diacetyl rest? What level of diacetyl do you have to be at before you have to worry about it not cleaning up during lagering?