Yes really. It depends on what type of worms you're dealing with. All dewormers are not equal and they do not allow treat all types of worms.
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Article 'Worming Chickens—Medicines and Dosing Information'...
You want to keep everything AS DRY AS POSSIBLE to prevent flies and maggots.
Can you post a few pictures of your set up?
I have shavings with a passion...I think they are nasty and stinky.
I use dirt and peat moss. I have no fly issues.