[Jimthebrewer123]

Hello I am about to brew my first lager. An I am doing some  research an I came across what’s call a Diacetyl rest now I read different methods on how a Diacetyl rest is  conductor. Like you do the rest at 50%,75%, or even after the fermentation is done I am confused about when to do one. Can I just let my lager go for like 10 days an then slowly ramp up to the 65f to 68f an hold it there for like a week an then ramp down 2 degrees Fahrenheit every 12hrs until I am at lager temperature 40-34f an lager for a fews weeks.

[dmtaylor]

Everyone does it a little differently.  I myself am not consistent with how I do it.  Also, if you don't smell or taste any diacetyl in the unfinished beer, you might not even need to do a diacetyl rest; HOWEVER, it will never hurt to do one either.  Your plan looks good, 10 days then ramp up, that should work fine.  Does it matter?  That's a question I cannot answer with absolute certainty.

If you do need a diacetyl rest, then the best time to do a diacetyl rest is when the specific gravity points are half of what you started with.  So for example, when a 1.060 OG beer changes to 1.030, or from 1.086 to 1.043, etc.

[Robert]

^^^^
Yes, if you want the simplest approach, at around 50-60% ADF just let the beer free rise to ale or ambient temperature.   No harm will be done -- all of the temperature related flavor development will have been accomplished in the first 1/3 of fermentation -- and you will quickly finish fermentation.   Then crash cool, and hold cold just long enough  to clarify.   So even if you don't need to reduce diacetyl,  you will quickly and effectively finish a lager fermentation with no risk. There's no reason to complicate things further.

[klickitat jim]

If I ramped mine up after 10 days it would likely be done fermenting already. Time is a good method of when to ramp if your experience dictates it as such. With my lagers I know that I'm around 50% ADF at about day 4.

[denny]

If I ramped mine up after 10 days it would likely be done fermenting already. Time is a good method of when to ramp if your experience dictates it as such. With my lagers I know that I'm around 50% ADF at about day 4.

Yep, same here.

[ynotbrusum]

I find it to be strain dependent and then within the strain - temperature dependent, but a good healthy pitch of lager yeast typically is halfway there at a mid to high temp lager fermentation (with respect to mfg specs, but say at mid to upper 50’s) in 4-5 days, but I have experienced occasions where it is slower - finicky buggers sometimes!