Mr. Matly yeast calc.

So looking at the mr.malty yeast calc, what exactly is the growth rate on the bottom? How is that determined ?

JZ did years of research on yeast growth rates based on a number of variables. Those rates are based on his analysis of that data. It is not a constant, it is most likely a variable on size of starter and the viability of the yeast.

But I have the ability to change it. Just wondering what a good set point for the growth rate is, seeing how moving the growth rate between 2 and 6 has drastic changes to both the size of the start, and number if packets/vials to use.

907_fellow said:

But I have the ability to change it. Just wondering what a good set point for the growth rate is, seeing how moving the growth rate between 2 and 6 has drastic changes to both the size of the start, and number if packets/vials to use.

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IMO I would not change the growth rate that's set. The selection of using a stir plate, intermittent shaking or nothing will really determine the growth rate for you.

Unless you have a lab and the experience greater than those that created the site and its math it's best to just plug your numbers in for gravity, batch size, date if yeast and method of stirring/shaking

So leaving the growth rate at 2 (the lowest setting) is probably the best, conservative, approach? That's kinda what I assumed but didn't know for sure. This is what I got for my next brew...

There are multiple ways to get the same amount of yeast. You can pitch several packets into a small starter, or you can use a large starter with only one pack. The growth rate slider allows you to choose which approach you want to use.

I always adjust my growth rate so that I only need to use one vial/smackpack- that should change the size of the starter it suggests.

daksin said:

I always adjust my growth rate so that I only need to use one vial/smackpack- that should change the size of the starter it suggests.

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Ok. I will go that route.

AmandaK said:

JZ ...

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JZ?! Man, I love his song "99 Beers but a Bud aint one"!

tre9er said:

JZ?! Man, I love his song "99 Beers but a Bud aint one"!

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Heard dat!

Mr Malty is the best yeast calculator ever!!!!! Best $5 I ever spent!!!!!!!!!!!!!'

I'm leaning more towards YeastCalc for stepping up and simple starters, but Mr Malty for yeast slurry repitches.

I'm so glad Jamil Z invested all the time and effort into researching yeast so I didn't have to! Thanks, Jamil!

daksin said:

I always adjust my growth rate so that I only need to use one vial/smackpack- that should change the size of the starter it suggests.

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I do the same thing, but don't have the ability to do a starter bigger than 2L at a time. So I slide the growth rate until I get a starter under 2L, then buy that many vials.