If I do a 2 liter starter with one vial of WL0001 or maybe a Belgian Ale yeast, can I then repitch that yeast starter (after decanting wort) into another 2 liter starter wort and double it again? Or should I pitch half the yeast starter? I know the amount of growth is limited by size of the starter vessel, I use a 2 liter Erlinmeyer flask.

I don't know if it will double, but that's how I used do it. While I'm brewing I would decant and "feed" the yeast a third time. By the time the wort is cool, it is ready to pitch.
I know I am beating a dead horse, I switched to dry yeast late last year and love it. Dry yeast has improved over the last 10 years. One packet of dry yeast and you are done. Easy, simple and no worries if I have enough yeast cells.

The other option would be to wash the leftover yeast cake with "clean" water, water that has been boiled to sanitized it, let it settle for 15 or so minutes, then pour off the "heads", keep the "middles" and pour off the tails. This could be used to either pitch to the next batch or grow the next starter. The idea is to take the most viable yeast to pitch into the next batch. Check the forum for washing yeast and be sure to review the "washing yeast" episode of BrewStrong for more info.

hth,

So do you do starters with your dry yeast? How do you calculate your yeast counts? Thanks for the reply.

Thanks, Ive listened to that podcast, excellent. That is a good idea, something I hadnt considered. Thanks!

Dry yeast packs generally don't benefit as much from starters, for one, it's often not as much of a savings to do a starter vs buying another pack of yeast if needed. I believe Mr. Malty has posted counts for dry yeast by gram, I don't remember the number off the top of my head, but make sure to properly rehydrate the yeast.

Regarding your initial starter question, the rule of thumb I follow is that 1 liquid package has ~100 bil yeast. 1 package in 2L starter will double in cells to ~200 bil, but if you just switch out the wort, you won't get a doubling, instead you will end up with ~300 bil cells. I base this on the chart in Yeast.

Thanks. Was that a link to a book, Yeast? It didnt come through. Definitely appreciate all your feedback.

It wasn't a link, just underlined to signify that it was a title. It's the book written by Jamil Z and Chris White. It's available through the BN store... http://www.thebrewingnetwork.com/store/index.php?main_page=product_info&cPath=12&products_id=148