Hi there! As someone who's been raising birds for 11 years (and who proudly calls herself a bit of a "poopologist"—yes, I’ve spent way too much time analyzing chick poop!), I totally get your concern. Watery droppings can be alarming, especially when you’re preparing to leave them in someone else’s care. But rest assured, occasional watery poop—especially when the chicks are drinking a lot, adjusting to new feed, or just growing rapidly—can be normal. Since they’re energetic, eating well, and acting like healthy chicks, that’s a really good sign. You're already doing the right things by keeping their waterer clean and observing their behavior closely.
Now, regarding Corid and medicated feed—this is where it gets a little nuanced. Medicated starter feed typically contains amprolium, which helps prevent coccidiosis but doesn’t guarantee immunity. Think of it as a buffer, not a bulletproof shield. If just one chick has watery poop and there are no signs of lethargy, puffing up, or blood in the stool, I personally wouldn’t jump straight to Corid, especially if you’re not sure which chick it is. But if symptoms escalate while you’re away—such as more chicks showing symptoms or a clear decline in activity—it might be good to have Corid on hand just in case, with instructions for your chick sitter. Safe travels, and I’m rooting for your fluffy crew!
Grow some fodder? That slows the rate of consumption, and honestly is fantastic for them.