Re-pitch one batch old W34/70 (noob question)

[Yuz]

Hey Brewers,

I have a 10-day old live slurry collected from the current batch. I've collected about 200ml in total and diluted to 500ml with water to displace oxygen and stored overnight.

Now I want to decant the liquid, fill up to about half the bottle to lift the yeast off the bottom and pitch this mix into the new batch

Would this be enough for a 23L batch of 1.040? I estimate there's about 70-75g of live culture in total.
I've tried to use pitch calculators but have no idea as to how to estimate this in terms of cell count...

TIA!

 

[Jack of all biers]

If it were an Ale yeast Mr Malty says 73ml slurry is what you need. But given you have a Lager yeast you need around 140ml. Get a 1L starter going or pitch at Ale temps and reduce to Lager with your 70-75ml, but don't forget to raise for a D rest near the end of Fermentation.

For future reference, save this website to your favourites. You will use it often enough. http://www.mrmalty.com/calc/calc.html

 

[wynnum1]

You do not have to displace oxygen the yeast will take care of that .

 

[Yuz]

If it were an Ale yeast Mr Malty says 73ml slurry is what you need. But given you have a Lager yeast you need around 140ml. Get a 1L starter going or pitch at Ale temps and reduce to Lager with your 70-75ml, but don't forget to raise for a D rest near the end of Fermentation.

For future reference, save this website to your favourites. You will use it often enough. http://www.mrmalty.com/calc/calc.html

I'll be pitching at "warm" Lager temps (current Melb weather, averaged out to about 15deg.)

 

[Brewno Marz]

I also pitch slurry and 75ml after 10 days probably is just enough, provided you take Yuz's advice and pitch at around 15-16deg C, or even 18deg to be safe, as per Jack of all Biers. Lower to 14deg after 24 hours. I find W34/70 at 14deg C gives great results, so no need to ferment at less than this. Also, if you're pitching at 15 or 16 deg use the "Hybrid" selection in Mr Malty, rather than lager.

 

[Yuz]

Well, I've used the ~70ml collected and pitched into 21L 1.044 wort, took about 8 hours to fire up but now it's happily chugging away
I was concerned about under pitching and the donor batch being 1.040, so I dropped the volume for this exercise to up the fermentables density.
The stick on thermo tells me 18C, which was expected with current Melb weather. All good and will do it again
From the initial 15grams of W-34/70 I got three batches fermented.
Brew on!

 

[Danscraftbeer]

Its a good brewing skill to have up your sleeve. What I've found too my best beers have been the 1st and second recycle as a pattern. That may also be that its usually a higher pitch rate. With lagers recently I have pitched new wort onto the whole yeast cake and get very clean crisp Lagers. The pitch rate could be 4 times or more the recommended pitch rate. So generally over pitching especially with lagers is far less a concern than under pitching etc.

 

[Yuz]

Its a good brewing skill to have up your sleeve. What I've found too my best beers have been the 1st and second recycle as a pattern. That may also be that its usually a higher pitch rate. With lagers recently I have pitched new wort onto the whole yeast cake and get very clean crisp Lagers. The pitch rate could be 4 times or more the recommended pitch rate. So generally over pitching especially with lagers is far less a concern than under pitching etc.

Yeah, like with any hobby it's about acquiring skills and knowledge - and in home brew it's awesomely rewarding
The process is simple: Collect yeast from Fermentasaurus while the batch is still going, and use washed slurry in the traditional fermenter the same or next day. Three batches done so far with good results. I like the "overlapping" batch schedule too
Edit - so far I've only done this with Lager yeast, hope the Ale variety would also work.