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Harvested yeast and Mr. Malty

So I harvested some 1272 Wyeast about six or eight weeks ago. I have two 16oz mason jars with the yeast in them. There is about a 1/4 inch of yeast on the bottom of each jar. I figured I should make a starter and I was wondering if I should use both jars or just one. I’m going to use the yeast with a MB Cream Ale extract kit. The O.G is 1.040.

I checked Mr. Malty and I guess I don’t get how to use it when you are trying to determine the size of the starter when using harvested yeast (a slurry?)

Looking to brew in a few days and any advice is greatly appreciated.

Use them both. I’m guessing that 1/4 inch of yeast is about the same as a smack pack. Your slurry is around 20-30% viable. So then I went to the liquid yeast option changed the date until the viability was between 20-30. From there depending on you method of starter ( stir plate, shaking) you can adjust the volume of starter to match the yeast you have( roughly two 3 month old smack packs). Hope that makes sense. That is my opinion, and hopefully you will get a few more. :cheers:

How do you come up with the 20 to 30% viability?

1 jar with a 2L starter will double your yeast. Or just pitch 2 jars.

You would face a 25% viability loss per month. That should put your viability above 40% if stored properly. Depending on the thickness of your slurry, you could build a 1 liter starter from 250ml of thin slurry or 90ml of thick yeast.

I just put the date of harvest in and hit the slurry button. At 7 weeks old you will have 22% viability, because slurry doesn’t store as well as a smack pack. The only way to know for sure what you have is to put it under and microscope and count them. Call it a WAG or an educated guess as to what shape your yeast is in. Personally I would rather come close to over pitching than under pitching, and that is the reason for my first post. Good Luck :cheers:

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