I am starting to make two five gallon batches of all grain beer in a brewing session. I used to make only one. The two batches that I make are yeast compatable always. For a five gallon batch I use one tube of wyeast. I still only want to use one tube, but for two five gallon batches. I have been told that one tube may not have enough yeast for both batches, so my questions are: how do you make a good yeast starter? How long should it go before it is ready to split and pitch into both batches? Please help!