If you have that much ammonia then I will betcha anything you also have that much *humidity* in the coop, which stall powders etc will make a *little* difference but not really solve the problem.
So, I think it would really be worth your while figuring out what the problem is and fixing it, rather than relying on powders as a running band-aid for the situation.
What size are your vents, what size is the coop, how many chickens in it?
Do you use droppings boards, if so how often do you clean them, if not how often do you clean out the deposits of poo that build up below the roost?
Is there any possible source of added moisture -- waterer spills, waterer leaks, rain coming in through openings, leaky roof, leaky walls, floor on damp ground?
Your solution(s) will lie somewhere in the answers to those Qs.
Good luck, have fun,
Pat