Is a d-rest necessary if you carbonate in the keg?

Ingredients
1

I have a lager that is finished active fermentation. I am going to brew today and I thought about using some wort to naturally carbonate the finished beer in the keg. Since I am going to be keeping the keg warm during this krausening stage so do I need to keep the beer on the whole yeast cake like in a normal d-rest or will the carbonation activity be sufficient to clean it up?

2

I have never tried that in the keg, adding wort would be adding Speise (food). It may cause enough activity to clean up the D.

Edit - you can taste the beer to see if it has Diacetyl to begin with.

3

Thanks Jeff.
I have never tasted diacetyl unfortunately. I think I am pretty much blind to it so I do a rest for the few lagers I do just in case.
I was also thinking when I do a big batch this would let me d-rest it without having to figure out how to warm 150 lbs of beer.

4

OK, that should work then. Prime with the Speise, and let it carbonate at room temp. Find someone who is sensitive to give it a taste.

5

If it’s stopped attenuating, it’s a little late for a diacetyl rest anyway. You may get even better results by going the spiese route.

Do you have a calibrated PRV for the keg? To carbonate at room temp you’ll need to hold ~30 psi.

6

PRV?  I am gonna say no since I don’t know what it is.  I can put it on gas after if necessary. Just trying to do a d rest and save CO2 at the same time. After it will go into my keg freezer to lager until I need it and let it settle.

I was going to use 10% of the volume of the keg (2L) based on what reading I had done on the topic. Thoughts?

Also not brewing today after all. Devoting the day to getting my CIP system working to clean fermenters and kegs. Just a 1/6 hp submersible pump stuck in my brew kettle and the fermenters sitting over to cycling hot PBW through. I can’t reach my fat arm into the brewhemoth opening.

7

PRV=Pressure Relief Valve

8

Or you can use a spunding valve, if you have one…