Following our discussions last evening regarding yeast starters I thought it would be beneficial to dig up a little information and get it out to those interested. I will also post in on our website too.
Here is a PDF from Northern Brewer that is pretty close to the process that I’ve been using for several years. I however use a airlock and stopper rather than the foam stopper they list. http://www.northernbrewer.com/documentation/YeastStarter.pdf
In addition to this I put mine on a stir plate to continuously agitate the yeast in the starter. If I really want big happy yeast volumes I will attach my aquarium pump to the stopper with two holes so I can continually aerate the starter. So in that case the stir plate is continuously agitating the starter and allowing oxygen to be dissolved into beer and feed the yeast. The system would look basically like this and I wouldn’t go this far all the time.
You do not need to purchase a commercial stir plate and can easily make one with an old computer fan and some miscellaneous parts from Radio Shack: http://www.instructables.com/id/Cigar-Box-Stir-Plate/
Here is a nice video showing a similar process from BYO magazine and Basic Brewing: http://www.youtube.com/watch?v=aAssRh_O6fs&feature=related
Also, this link is a reference I use to determine how much yeast ‘should’ be pitched into a beer depending on its starting gravity. http://www.mrmalty.com/calc/calc.html
Ok I hope that helps!