You'll need a fairly fine mesh to sift tiny chick poops, I use window screen when they're really little,
but that will sift out some of the larger PDZ granules( you got granules, right, not powder?).
Have Cheryl check this out:
https://www.backyardchickens.com/t/...raphic-gross-poop-pictures/1100#post_13179595
Might give y'all some ideas....is she reading the forums too?
Just keep tapping the nipples until they get it....hopefully one will catch on and teach the rest....
removing all other water sources is key.
I've had some get it right off the bat, and others take a week or two...SHM...might have to put down a regular waterer at the very end of the day if you feel they may be dehydrated, then remove it after they've gone to sleep and try again the next day.