Why do my chicks keep getting sick?

Hoping some of you can help me figure out what I'm doing wrong. This is the first time I've had chicks and I can't figure it out.

Three weeks ago, I picked up 5 chicks from a local breeder. 3 were 3-ish day old Marans and 2 were 2-ish week old Easter Eggers.

One of the Marans never seemed happy. After a while I noticed that something was wrong with its feet. It looked like there was sand or poop encrusted on its feet, but I soaked its feet for a while and scrubbed gently with a toothbrush and it didn't come off. I had kind of decided it had bumble foot and had decided the best course of action would probably be to put it down, but the next day it died on its own.

The rest of the chicks seem super happy and are very social, but just today I noticed some bloody stools. I've at least seen it coming from both Easter Eggers, but am imagining the remaining Marans are affected too since they're all sharing a breeder. From comparing photos here I think they have Cocci. The feed store is closed today but I'll pick up some Corid tomorrow and start everybody on that. In the meantime I added Braggs apple cider vinegar to the water.

I have all the birds together in a breeder I made from a big plastic storage box with hardware cloth taped over a cutout in the lid. I started with a bed of wood shavings in there but it seemed hard to keep that clean, so I switched to sand with some Sweet PDZ and DE mixed in. I clean it every afternoon by shoveling the sand, shaking it out through a sifter, and throwing away the poops. There's a Brinsea heater for them in there. It's in a garage that stays temperate. I have two nipple waterers made from gatorade bottles with vertical nipples. I fill them daily with water mixed with chicken probiotics. Every afternoon I fill one of those galvanized feeders with lots of holes with a mason jar on top with medicated chick starter feed. They immediately take it all out of the feeder and eat some of it, then eat a lot of the rest off the ground over the next day. They don't seem interested in treats but I've still offered them live soldier fly larvae from my compost bin, dehydrated mealworms, and some grass. They might have pecked at it a bit. They have access to plenty of grit with the sand in the brooder.

I don't get it. I'm doing everything I can think to do to keep these chicks healthy but they keep getting sick. Does anyone have any ideas as to what I could do differently?

Thanks in advance for any ideas, and for reading my long post!

Jen

I think what you're asking for is reassurance that you're doing everything you reasonably can do, and that it's probably not anything you're doing wrong that's causing these problems to keep occurring. So, here it is.

I see nothing in what you're doing to indicate that you've messed up in some way. Sometimes, conditions are just what they are and sickness happens. You appear to have a good understanding of how to care for chicks and what to do when these situations arise.

I hope your chicks get better, and there's no reason to think they won't. If you have another chick die for mysterious reasons, you might do well to have a necropsy done so you know what you're dealing with.

Other than that, keep up the good job. You're taking very good care of your chicks as far as I can see, and I'm sure you'll take Karen's advice and get some chick grit.

You might also switch back over to shavings. If theyre making a mess with the water, maybe its dripping, the tub bottom might hold that, allowing the cocci damp conditions to thrive in. Just a thought.

But I agree, I see nothing you're doing wrong and sometimes things just happen.
Good luck, chin up

Thank you to all of you! The chicks made it through the night and this morning when I put down some of their feed mixed up with medicated water, they ate it with gusto, so I think we're out of the woods now. It really does help to know that I seem to be doing okay and sometimes these things just happen. I so appreciate all of your responses.

I didn't realize about the chick grit. I picked some of the right kind up at the feed store this morning and will give that to them the next time I put them out in the coop. So glad you mentioned that. I will probably finish building the coop today and with any luck they'll be in there permanently soon, so the sand and plastic won't be an issue.