First, unless you discard, eventually you'll end up with The Sourdough That Ate Your Kitchen– too much starter. Second, keeping the starter volume the same helps balance the pH. And third, keeping the volume down offers the yeast more food to eat each time you feed it; it's not fighting with quite so many other little yeast cells to get enough to eat. The discarded portion can be saved and used in many of our recipes for added flavor and texture but no rise. Look for recipes that call for unfed or discarded starter to use it up!

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