Hi Judith! The doubling and shrinking is indeed quite normal. As your starter "eats it's food" it will grow and once it has run out of food it will shrink back down. It sounds like your starter is quite active and once it is doubled in size you can harvest the amount needed for your recipe and bake with it! In between baking with it you can store it in the fridge and feed it once a week. Happy baking!

• Reply