Chef Fleck taught us how to feed sour dough culture today. He had two cultures going, one from nasty rotten grapes and one from left over beer slop. Yum. He drained off the liquid and added back either 1:1 of water and flour or 1:1 of water and red (rye) flour. Stir until well mixed. Cultures can apparently survive in the refrigerator for a long long time (per Chef Fleck, up to 3 mos.).
*"Feed the Beast" is a reference to Kitchen Confidential