Equal parts rye flour and water does the trick. Just feed it once a day - take out a portion of the existing starter (say 1 pound) and add equal parts rye flour and water. Rinse, repeat... Here's a killer recipe I made just last week, sorry for the large numbers, but make big batches. Also made using a large 40 quart mixer, so not sure how this would translate into a home environment. You could divide it up or use baker's percentage I suppose... Caraway Rye Sourdough 2#2oz. high gluten flour 2#2oz. organic whole wheat flour 1#2oz. coarse rye flour 3#10oz. rye starter 3#10oz. water 1 oz. fresh yeast 2 1/2 oz. salt 2 oz. caraway seeds 1- Straight mixing method (5 minutes at 1st gear on Hobart). 2- Bulk fermentation for 1 1/2 hours, perform a fold/turn at 45 minutes. 3- Scale out 1 1/2 pound loaves. Bench rest before shaping. I make rounds and proof in baskets dusted with rye flour, but suppose you could make batards or some other shape. 4- Final proof 1-2 hours 5- Bake at 425F with steam. I use a docker on the top of the round before loading it in the oven rather than scoring it. It is a wonderful and fragrant bread. Taste good right out of the oven and even better the next day. Devin