I'm sorry for your losses.
Coccidia are found in poop and soil, but hopefully being in a different environment may help...
If you are raising chicks in a brooder, then introducing them early to things they will encounter when you put them outside may be helpful.
I usually try to brood outdoors near my flock, the area they go into is "dirty". Meaning the adults have been in that pen/brooder area most of the year, they have pooped in there, etc. I do clean/sweep it out but don't go overboard sanitizing. There's some dust and bits of dried debris/poop in there of course. I also give the chicks a pan of sifted dirt directly from the run, this is usually mixed with a bit of peat moss or a plug of sod from the yard. The sifted dirt definitely would have whatever the adults have in it. This is how I "expose" chicks that I brood. I prefer broody raised, but that's not always possible.
I do keep Corid on hand just in case. Keep the brooder dry, clean up any water spills for sure and keep water stations clean of poop. I just dump water, rinse them stations and give fresh water several times a day.
It does seem some folks have more trouble than others and Corid is just not as effective as it used to be for some. If you find that is the case, then having Endocox (Toltrazuril) and/or a Sulfa Antibiotic on hand is a good idea. IF you find the Corid is not helping, switch to one of those.
As for DE drying out poop, I'm not sure how that would work. DE can be a bit irritating to the respiratory system, so if you plan on using it, use a small amount and make sure ventilation is adequate.