Hi Patrick, during the creation process a sourdough starter is more vulnerable to mold and unhelpful bacteria because it has not yet developed the natural defenses that a mature starter possesses. During this time, stirring the starter well after each feeding can help prevent mold from taking root (mold needs oxygen to grow and starts on the surface, so stirring the starter well each day can help disrupt mold development). It really isn't necessary to clean the container each time you feed your starter, but it can be helpful to scrape down the sides with a silicone spatula. If you're not already doing so, I'd also recommend covering your starter container with plastic wrap or a lid set loosely on top. Once your starter is rising, it's important to begin twice daily feedings. Ideally you don't want to let the starter fall significantly between feedings when you're maintaining it at room temperature. Feeding it in this way will help keep your starter healthier and more active as it matures. 

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