Starter from old wyeast smack pack

[RichC]

I've a smack pack dated september2012 of wyeast 3068(weihenstephan strain). I've been trying to calculate what size starter I need(not something that normally bothers me but as a matter of interest). Mrmalty tells me I need 7 smackpacks and a 1 litre starter and I've 10% viability and yeastcalc tells me I need 1 pack in a 2 litre starter and I've 1% viability. I'm using a stirplate. See screen grabs of 2 calculators below. Can anyone explain the 'huge' discrepancy for me please? Am I using them correctly??

Thanks!

[Ciderhead]

Mr Malty always seems to generate more questions than answers
Keep it simpler, was that the production date or expiration date?
If its the prodction you are fine to pitch directly as per instructions.
If its the expiration a very simple rule of thumb is one day for every month that you are over so min six days on the stir plate, consider 2 goes at it, so a 500ml batch, settle 8-12 hours in fridge, decant, and a 1 litre to get it really back to full viability.

http://www.wyeastlab.com/hb_makingastarter.cfm

[RichC]

Thanks CH, that's production date and I read somewhere that it'll need a starter after  about 6 months. I'd still really like to understand the calculators? Anyway I'd rather slightly over pitch because I don't like my hefes to be overly strong on the banana and apparently under pitching brings that out more with this strain. Also, is decanting a starter a good idea with a low floc strain like this as surely I'm just keeping the highly flocculant yeasts?
Thanks !

[Ciderhead]

Wyeasts are ok up to 6 months, pop it and watch how quickly and big your bag fill out?
I'm with you I always try to marginally over pitch to make sure I get a solid start to fermentation, so just go with a 500 ml starter?
I use beersmith and also app on the iPhone, the calculators are fairly wysiwyg.


If you want to know the detail, bed time reading
https://www.homebrewersassociation.org/attachments/0000/1235/MAzym07_YeastStarter.pdf

[RichC]

Thanks CH. I'm going to read that PDF. I actually have the yeast book but I'm quite haphazard about my starters. I usually have plenty of viable yeast but like to waken them up with a small starter. However, I intend figuring out what's going in with those calculators!