I agree. Something isn't working right. or....I just cant figure out how to utilize beersmith with yeast ranching.
I've mentioned before, I farm my own yeast. I freeze 15 ml of slurry with 15 ml of glycerol...roughly 18 billion cells per vial. I pitch this in 100 ml of wort, then step to 500 ml, then to 1 l, then I will decant and add a second 1 l of wort to the same flask. This gives me something like a 20:1 growth factor...limited by maximum cell densities in a 1 l flask (~220 billion cells).
So, I create inventory items for my "hampton labs" yeasts with all the relevant facts. I change the "form" to culture, so that I can set a different age rate. Then I use these inventory items in my recipes.
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[*]I add the yeast to my recipe, and beersmith calculates the viable cells at 14.4 B. It also tells me the number of cells needed (eg. 233 B).
[*]I use the "yeast packs to use if no starter" value as a guide for the amount of growth required. I don't really use it for anything, but its nice to see how much growth is required.
[*]I don't really know what to do with the "recommended starter size". The number doesn't seem right to me. In my example, BS is saying 0.84 l. But, I think 233 B cells is more than 1.0 l will support (density wise). 1.05 l seems closer. I seem to be able to adjust this with "stir plate factor". I've settled on 2.35, but that seems like a hack for BS overestimating the cell density that can be supported without a stirplate.
[*]Now, we get to "yeast cells with starter". I can't get this number to make any sense to me. No matter what I do, I can't get it to exceed 86.5 B in this example (a growth factor of 6.0). I've set "growth factor limit" to 1000, so it stays out of my way. I've tried changing the starter size, and the stir plate factor...both to no avail.
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As I've worked through typing this, I think I've worked it out myself. Growth factor seems to be internally limited to roughly 6.0. For those of us who "ranch" this doesn't really work. I can't grow enough slurry to store 100 B cells per vial. Well...I could...but I call that beer, not starter.
The information I need is really this: 1) the optimal starter size for the initial step based on viability, and a desired pitching rate (~ 100M/ml). 2) The number of decant-step cycles required at my final volume since maximum concentration isn't generally reached when stepping from a smaller volume. The intermediate steps are just mechanics depending on what step ratio I choose (2x, 4x, 10x, etc).
My point in (2) is that if I step from 100 ml to 1000 ml (10x step up), I will end up with about 100 M/ml density...or roughly half of maximum. If I decant and add another 1000 ml wort, I can get to the maximum of ~220 M/ml ( or 220 B cells) without using a larger flask.