Reducing Ammonia Levels During Brooding

Your chicks have just arrived and the level of ammonia in your house seems a little stronger than you would ideally like it to be. Your serviceman arrives and checks the ammonia concentration with a draw tube and finds that it is over 50 ppm. You are already operating a couple of 36" fans one minute out of five and are not crazy about the thought of increasing your fan run time considering the fact that it is supposed to be below freezing tonight and propane is over $1.50 per gallon. What do you... do?