Pinkish/reddish color in chick poop
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Looks like it could be Coccidiosis. You will need to treat them with Corid.
Dosage for Cocci is 1 1/2 teaspoons Corid powder per gallon or 2 teaspoons of 9.6% Corid liquid per gallon
Give for 5-7 days - make sure this is the ONLY water available during that time period. Mix a fresh batch at least once a day.