Ammonia and moisture: causes and fixes
Where ammonia comes from in a coop, why a sharp smell means the flock is already breathing it, and the order to fix it in.
If you can smell ammonia walking into the coop in the morning, your birds have been breathing it all night.
Ammonia rises from wet droppings as bacteria break them down. The smell is the symptom. The cause is moisture not leaving the coop fast enough. Bedding gets damp, droppings sit in damp bedding, bacteria do their work, and ammonia comes off the floor at bird level where the birds are sleeping.
Fix airflow first, bedding second, water third. Adding more vent area on the high outlets is almost always the right first move. The University of Maine Cooperative Extension formula of 144 sq in per 10 sq ft of floor is a floor, not a ceiling, and humid environments need more.
Bedding next. Pine shavings stay drier longer than straw or hay. Replace before the moisture wicks up to the surface, not after. The deep-litter method works in some climates and fails badly in coastal humidity.
Water last. Move waterers outside if your coop has space constraints. The single biggest moisture input in most coops is a dripping nipple-bucket the keeper never noticed.