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How much yeast after wash?

How much yeast will I have if I wash/rinse from my primary? I’ve been scanning the internets for several days now, found this question asked numerous times but nowhere did I get a precise answer. In the end it sounds like I am over analyzing the question, but here is what I am going to do.

I have two primary’s that are ready to be racked to kegs. Original gravity was 1.048, used WY 1056. I am brewing eleven gallons of a 1.065 Dale’s Pale Ale clone this weekend. I was going to pitch on the yeast cakes, but the krausen ring and trub content has got me thinking about washing/rinsing the yeast and starting with clean carboys.

I am going to use Billy Broas Yeast Washing technique

on one (1) of my finished carboys which should yield two quart sized mason jars with about an inch or so of clean yeast. I am going to start the yeast washing tonight to give the final rinse jars two days to settle in the fridge. I would love to know how to define my slurry for mr. malty’s calculator, but since that question seems open to much debate, here is what I want to do.

If I take one of the two jars from the fridge brewday morning, let it warm up, decant the clear liquid from the yeast, then pitch the clean yeast into the two clean carboys split over the 11 gallons of fresh Dale’s Clone, will I be pitching enough yeast? In effect I am pitching one quarter of the yeast that I would have if I pitched directly on the yeast cake. My assumption is I am pitching more than enough, and will still get good yeast growth in the early going. The other thought is to pitch the two jars of clean yeast, in effect splitting a single yeast cake over two fresh carboys.


[edit] Anyone know how I can calculate how much yeast I had in the carboy when it was done fermenting? Seems like I can divide that number by 4 to get my answer.

At an OG of 1.065, I’d suggest a 3rd of the yeast from a finished fermentation for each 5gal batch. Collect and rinse your yeast into 3 containers. Save one for a future batch and pitch a jar into each 5.5 gallon batch.

As for mr. malty with the slurry…I rarely use it. I just use the Rule of Thumb that 1/3 of the yeast cake will ferment a batch of ale up to 1.080.

For a lager, use half a yeast cake up to 1.080.


Thanks for that mvsawyer, sounds like a useful guideline. Since I was thinking about another way to calculate the total cells in my finished carboy I worked out the below…

Using the Wyeast calculator:

step 1 - I plug in my starter method (activator pack in half gallon starter on stir plate)
step 2 – I plug in my primary fermentation volumes of 5.5 gallons, no stir plate.
step 3 – here is where I think I can calculate the final concentration of yeast cells. Since I cant plug in zero for “additional wort added”, I plug in .001 gallons to get close to zero. Step 3 now shows a final pitch rate of 55 million cells/ml

Ok, so if my assumption in step 3 is correct, 55 million cells/ml is my final yeast concentration and what I use to determine the number of cells grown in primary fermentation. 55 million cells per liter works out to 208,175 million cells per gallon, or 1,145 billion cells in the entire 5.5 gallon batch.

If I figure I am using ¼ of a yeast cake, that works out to 286 billion cells pitched into each of the two carboys of finished Dale’s wort, or 382 billion if I take mvsawyer’s suggestion and use one third of the yeast cake. If my calculations are correct, that puts me above the 247 billion cells Mr. Malty says I need.

Now it feels like I am totally over thinking this, but is it safe to assume that a portion of these 286 billion cells are dead or did Jamil already account for that in Mr. Malty’s calculation?

This is just me but, in order to save space and not have a ton of yeast laying around and to avoid under pitching I normally split my yeast cake into two jars and then make a small starter to get them back up and running before use. That starter not be necessary for you seeing that you’ll be pitching pretty quickly.

Just do some experimenting and see what works best for you. There are a lot of ways to go about saving and reusing yeast and it can be a bit tricky at first choosing you path.

[quote=“cam0083”]That starter not be necessary for you seeing that you’ll be pitching pretty quickly.
Yeah, I am going to skip the starter since the yeast will only be chillaxing for a few days. After I cool my wort, I typically whirlpool and let it settle for 30-45 mins. I think I will add some cooled wort to the decanted jar(s) before I whirlpool. By the time I pitch, the yeast will have an hour+ to wake up before the main course.

The amount of yeast you can rinse and collect will be different from batch to batch and depending on the yeast. Some yeast (Wyeast ESB 1968) flocculate so quickly that’s it’s almost impossible to rinse the trub. It drops out faster then the trub does so you get a yeast layer on the bottom and the trub above it. Others like wyeast 3068 weihenstephan weizen are very slow to floc, so they are easier to rinse and collect. I generally get between 1 and 3 jars of good yeast. Another factor is how much crap is in your yeast cake. Some people just dump the whole pot of wort in their primary so there will be a lot of crap in there. I don’t because I like to rinse and collect. I also rack my beer to secondary if I’m dry hopping so to not get hops in the yeast. That’s actually a perfect time to rinse.

Anyway, over time you’ll get to know which yeasts are easier to rinse and which aren’t even worth the time.

I would love to know how to define my slurry for mr. malty’s calculator, but since that question seems open to much debate[/quote]
Pretty self explanatory. Set the calc to 1B/ml for thin slurry, or up to 4B/ml for thicker slurry.

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