Chicks tend to have runny poops, but just keep an eye on them. Get some Corid just to keep around, since it can become scarce in spring and summer. If I were going to treat with Corid, I would not separate it, but treat all of the chicks. Dosage is 2 tsp of the liquid, or 1.5 tsp of the powder...
Watch for any lethargic chicks, standing hunched or puffed up, or not eating. That with runny poops or blood could be coccidiosis. Corid liquid or powder for cattle treats that. Cecal poops are fermented in the cecal pouches between the small and large intestines. They occur several times a day.