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-   -   yeast calc confusion (http://www.homebrewtalk.com/f39/yeast-calc-confusion-365314/)

frostyp 11-03-2012 09:44 PM

yeast calc confusion
Just building a stir plate so i can improve my lagers/ales utilising the correct amount of yeast.
Looking at mr Malty and yeastcalc, but to be honest i dont understand them, how do i know what the gravity will be before i make the wort? so how do i know what to put into calculator??
is there a rule of thumb on how much yeast, dme i would need to make a litre starter? have only used the packaged yeast in the kits up until now, initially thinking to put these in water/dme to make a starter but upon reading posts that it isnt a good idea with dried yeast, so ok ill buy the liquid yeast if that is what i have to do, but how much? God im confused

Golddiggie 11-03-2012 09:58 PM

I use BeerSmith to formulate my recipes. Once you've calibrated/broken-in your system you should have a pretty stable efficiency. As such, you can get the OG of the batch (within a few points typically) that you can use in either tool.

I prefer the yeastcalc.com tool mostly because you can opt to make a stepped starter (up to three steps). Combine that with a stirplate and you can make the yeast cell count you need while using far less DME in the process. I did that for last weekend's batch, making three starter steps (1.6L, 1.8L and 2.2L) when I would have needed to make more than a 20L starter if it was as one step.

BTW, as long as you're within 5-10% of your needed cell count, you should be fine. I try to get closer to the count needed, but I don't worry if my batch OG is above, or below, the projected/expected by a few points.

frostyp 11-03-2012 10:14 PM

Still sounds complicate I think I need find a walkthrough explanation of how to use

Golddiggie 11-03-2012 10:21 PM


Originally Posted by frostyp (Post 4556111)
Still sounds complicate I think I need find a walkthrough explanation of how to use

You built a stirplate but you need someone to hold your hand on how to use a very simple online tool?? How much have you been drinking???

It's beyond simple...
Enter the information for the "Liquid Yeast Properties" section, including the production date of the yeast (and how many billions of cells the package is supposed to contain). Enter the information in the Wort Properties section too. Then go to the '1st Step' and select 'Stir Plate' and then start entering a starter size (in Liters) and see what you get for cell count. When you get the "Total Cells at Finish [billions]" to match (or within a small margin) what you need for the batch, you have the starter size. If you think that's too large a starter, or your flask isn't big enough, then use the "2nd Step" section. You can go up to three steps with the yeastcalc.com tool.

There's even the DME calculator so you know how much to mix. Although most people simply use 100 grams of DME per 1L of [finished] starter wort. I'm talking about volume post boil. I typically add a little to what goes into the pot (water volume) to offset boil-off. Usually .2-.3L extra for a 10 minute hard boil.

frostyp 11-04-2012 01:15 AM

Appreciate the explanation

Golddiggie 11-04-2012 01:18 AM


Originally Posted by frostyp (Post 4556485)
Appreciate the explanation

Didn't intend to come off too harsh, just never had anyone need it explained in that detail. Everyone I've talked with, emailed, etc. has been able to figure it out within moments of looking at it (and playing a bit). It was super easy for me to figure out the first time. Then again, I'm used to more technical things (in the IT field, working on [virtual] servers mostly). :tank::mug:

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