yeast cake

[crasher600]

Ok so i am just about finished primary of a pilsner for which i used 2x saflager s-23 yeast sachets, my next brew is going to be a coopers australian lager which i intend to lager for 4 weeks in my newly converted fridge :clap: . After syphoning off my pilsner is there any reason why i couldnt just put my lager kit straight on top of the yeast cake left behind and save £5 on yeast ?

 

[A T]

I've never done a lager but i have successfully pitched onto yeast cakes from ales plenty of times, i can't imagine that lager yeast would be any different :thumb:

 

[Parva]

You can and I've done it with success but I've only done it once and I was so lazy that I didn't even clean the fermenting vessel, I kegged the brew and dropped the new brew straight on top and it was one of my best brews to date!

There are a couple of points however. Firstly, the beer that's finished fermenting must be of a lower OG than the one that you are going to put the new wort on top of. The second point is that there's a real danger of 'over-pitching' the wort which can give off flavours. Given that an 11gms packet of S04 or Nottingham can ferment 23l of a potential 5% beer you are pitching maybe 100gms (total guesstimate but it'll be a lot).

I brewed a 5% beer, kegged that and dropped a 6.7% beer straight into the FV and it turned out great. However, if I were to stick closer to the original 5% that I started with I would probably take a few scoops of the yeast cake and add this to another FV rather than adding the whole lot.