Can you add more starter wort to an existing yeast starter?

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vast_reaction

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Hi everyone. First time brewer here, so I'm probably worrying excessively. :p I made a 1 Liter starter using White Labs Nottingham liquid yeast a couple of days ago, and I see a nice creamy yeast cake forming. After reviewing my recipe though, I think I need way more than 1L. (OG will be roughly 1.090)

The question is, can I boil up another batch of wort with my DME and yeast nutrient, and dump it into the existing starter to beef it up to 3 or 4L?
 
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vast_reaction

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Oh. Well, hot damn! Incremental Yeast Starter Stepping-Uppery, here I come.

Thanks for a swift useful reply!
 

el_caro

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Hum. I've always decanted off the old starter. Thanks for the tip, Revvy
Why would you not decant of the spent wort unless the yeast are still in suspension which they should not be if you have turned off the stir plate and they have finished feeding.
It really goes back to what you are trying to achieve with this starter. How many cells are you aiming for?
If you leave spent wort in the container that limits the amount of fresh wort you can add and hence the number of new cells that you will achieve with the 'step up' .
If you have a 1L starter and when it is finished just add another 1L of wort without decanting, then you do not really have a new 2L starter. You really are starting again with a 1L starter to which you have added a greater number of cells.
If you were to decant and add 2L of fresh wort you could expect to get a significant increase in total cells over what you would have got with just adding 1L of fresh wort.

I always pour off and then add the fresh wort.
 
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So should we just add the new starter wort to the existing wort trying to double the initial volume or should we decant the initial wort off of the yeast and then add about twice the initial volume of fresh wort?

Will this depend how long the starter has been going? I am curious because I want to double the amount of a certain liquid yeast that I can only get mail order to make a double batch size recipe (10 gallons instead of 5 gallons) and I am interested in the best way to do this.
 

Dunerunner

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I feed my starter every one or two days to build for pitching. I never pour off any of the starter beer. No issues yet.

I would suspect that if I were building a huge starter from very little yeast over the period of two weeks or so, I would chill the starter to floc out the yeast and pour off the beer.
 

el_caro

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I want to double the amount of a certain liquid yeast that I can only get mail order
If you want to double the quantity of cells of the liquid yeast package and do not have a stir plate then you would normally start by putting it into a 2L starter and that should do the trick. With a stir plate you will probably near treble the number of cells with a 2L starter.

Since you started with 1L you probably have around 150bn cells now (1.5x original).Adding another 1L to the existing would get you to around 200Bn cells (2x original) assuming no stir plate.
 
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If you want to double the quantity of cells of the liquid yeast package and do not have a stir plate then you would normally start by putting it into a 2L starter and that should do the trick. With a stir plate you will probably near treble the number of cells with a 2L starter.

Since you started with 1L you probably have around 150bn cells now (1.5x original).Adding another 1L to the existing would get you to around 200Bn cells (2x original) assuming no stir plate.
I have a stir plate and two 1 liter flasks but I do not have a 2 liter size flask yet. I am wanting to use a vial of White Labs Kolsch yeast and try to get enough for a 10 gallon sized batch instead of doing a 5 gallon batch and then washing the yeast. Normally waiting to get a 5 gallon sized batch done and then washing the yeast for other batches would not be a problem but I am entering a time of the year where I will not be brewing until spring due to a new baby arriving.
 
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