Well for that many birds I would suggest a flock treatment in the drinking. There are a variety of medications which different ones will be suggested by different people (by their preference). Appertex is tablets given individually by mouth,and isn't cheap. Go to foyspigeonsupplies.com and look under coccidiosis in product section. Albon is a good flock treatment and stays in the system for 12hours, foy's 4-1 is the most popular but there quite a few drugs on the market. If you have it in your loft (cocci) it is recommended that you treat periodically (time to time) and rotate medications,as the parasite may reinfest your flock under stressful times,since some infected birds may become carriers.
Has anyone used fenbendazole for cocci in pigeons?
It works great on cocci and giardia in dogs, as well as all types of worms including the hard to kill tape and whip worms and can be bought at most feed stores and Tractor Supply.
It is commony sold as Safe-Guard.