Yeast starter question

[TonyCall]

Calling all yeast experts! I am making a yeast starter from a one month out of date sachet of WLP004 Irish ale yeast. I want to use it in a 120 litre brew but don't really know what I'm doing! I bought a stir plate, flask and cans of starter wort, I think I worked out that I would need to make a 3 litre starter to produce enough viable yeast. 36 hours later the liquid in the flask, looks like fermenting beer, it has a good head of krausen developing, and the wort has become cloudy, so it all looks encouraging. However is there a time that I should turn off the stir plate in order to let things settle? How will I know that it's ready?

 

[Stu's Brews]

Calling all yeast experts! I am making a yeast starter from a one month out of date sachet of WLP004 Irish ale yeast. I want to use it in a 120 litre brew but don't really know what I'm doing! I bought a stir plate, flask and cans of starter wort, I think I worked out that I would need to make a 3 litre starter to produce enough viable yeast. 36 hours later the liquid in the flask, looks like fermenting beer, it has a good head of krausen developing, and the wort has become cloudy, so it all looks encouraging. However is there a time that I should turn off the stir plate in order to let things settle? How will I know that it's ready?

My process for yeast starters looks something like this:

• ~72 hours before pitching - pitch yeast into 1.037 SG wort and leave on stir plate at room temperature (~18-20degC).
• ~24 hours before pitching - turn off stir plate.
• ~18 hours before pitching - put starter into fridge to encourage yeast to settle to bottom of flask.
• ~6 hours before pitching - remove starter from fridge to allow it to come up to room temperature (~18-20degC).

Generally speaking, I wait until I can no longer see bubbles of CO2 forming before turning off the stir plate. I then leave it a further 6 hours to help make sure that it's fully completed (I also read somewhere that this is good for the yeast health but I can't remember the exact reason off the top of my head).

 

[TonyCall]

Thanks Stu's Brews, very helpful.