Hi Magda, I think it might be worth trying to save this one, since "pinkish water" doesn't sound like an absolutely definitive sign that your starter has spoiled. I would pour off the liquid and feed some of the healthier-looking starter from the bottom of the container. Give it twice a day feedings at room temperature for 2-3 days. If your starter begins to double in volume 6-8 hours after a feeding, has a pleasant aroma, and shows no more pinkishness, then you should be good to go. Keep in mind that when you're storing your starter in the refrigerator and feeding once a week, it's important to allow the starter a few hours at room temperature after you feed it and before you return it to the fridge. You want to see the starter begin bubbling and fermenting before refrigeration. Sticking it right in the refrigerator could result in a starter that doesn't have a chance to ferment properly and doesn't develop the proper acidity. Ultimately this could lead to a starter that is less resistant to outside invaders. 

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