Lagers & diacetyl rest

[Sandimas]

Currently brewing a lager with a true lager yeast, it's been sat bubbling away at 12C in my chilly downstairs loo.

Just wondering when is the best time to bring it into the warm for a diacetyl rest? It's on Day 7 now, it's been a few years since I brewed a lager and I seem to remember it taking 3 weeks to ferment out before, but I don't want to leave it too late before warming it up for 48hrs. Any thoughts?

 

[MrRook]

Currently brewing a lager with a true lager yeast, it's been sat bubbling away at 12C in my chilly downstairs loo.

Just wondering when is the best time to bring it into the warm for a diacetyl rest? It's on Day 7 now, it's been a few years since I brewed a lager and I seem to remember it taking 3 weeks to ferment out before, but I don't want to leave it too late before warming it up for 48hrs. Any thoughts?

What yeast? Not all lager yeast needs a d-rest.

 

[djheaton321]

I tend to wait until about 60-70% attenuation, about 10 days for the last couple I did (though this will vary with the yeast, OG and conditions). You can do it earlier. I got some inspiration for the way I do it from Brulosophy. He recommends 50% attenuation before upping the temperature. The first time I did it I missed this target and ended up starting the diacetyl rest at 70% attenuation. The lager was fine, very good in fact. I don't fully follow this fermentation schedule. I do let it lager for 6 weeks. I always end up with a very clean tasting and clear lager. Bear in mind there's more than one way to skin a cat!

 

[Sandimas]

Saflager S-23 yeast.

I'll give it a few more days then. Looks like temps are rising later in the week so the house temp may move up a bit anyway, it's not normally 12C in the house in April!

 

[BeerCat]

+1 for the brulosophy method. Been drinking lagers 1 month old and they taste great. So good in fact i have not made much else lately.

 

[Zephyr259]

+1 for the brulosophy method. Been drinking lagers 1 month old and they taste great. So good in fact i have not made much else lately.

I've got a Munich Helles planned and was thinking of using the brulosophy method. Do you go by gravity, taking a bunch of samples or just estimate by time?

 

[BeerCat]

I've got a Munich Helles planned and was thinking of using the brulosophy method. Do you go by gravity, taking a bunch of samples or just estimate by time?

I leave it about a week then ramp straight up to 18c for a week before crashing. After a few days at 0c i add finings and keg a few days later. Nothing very precise time wise. I also pitch cold if i can around 7c.

 

[Zephyr259]

Thanks. I'll be bottle conditioning but the rest sounds straightforward enough.

 

[krispn]

Here are two tips in one which might be useful for judging D rest times. I've read and experimented with this on
my first ever lager. Some circles say when you are about 8-10 gravity points off your expected finishing gravity is the best time to do a D rest. So if for instance you're expecting an FG of 1.014 once you're getting a 1.020 reading then commence your D rest.

A second useful tip if you have a stir plate is...

once you've pitched your yeast take a sample from your fermenting vessel (an appropriate volume in relation to your batch size) and put it back into your Erlenmeyer flask and get it on the stir plate (ideally at the same temp as the batch which you're about to ferment). Let it rip on the stir plate and it should ferment out after a few days. With this sample fermented take a gravity reading and you will now know the finishing gravity for your bigger batch. A D rest can now be planned more accurately as you know what the FG will be for that brew.

 

[Sandimas]

Thanks everyone.

I left it a bit late as it was 1012 by the time I dropped the hydrometer in on Day10. Kinda surprised by this as it was fermenting at the lower end of the temp range, 12C, and the last time I did a lager it was bubbling for 3 weeks. Anyway, moved it into the warm, and replaced the FV airlocked lid with a solid lid - I usually do this towards the end of fermentation, as once the lid stops bulging is usually indicated the brew is finished. It's been bulging a lot longer than ales usually do, so suspect it has a little way to go yet and is finihsing off very slowly, last time I brewed a lager it ended up at 1008.