I'm too busy and pressed for time to search the threads so I thought I'd kindly ask for some information from chicken gurus out there in backyard poultry land. I have a closed flock of heritage breeds that have as of 3 days ago started to drop due to a fungal growth. I'm deeply bothered and upset with myself for any improper management. I have a 12' X 24' chicken barn with gable vents on either end, a roof vent and a 2 X 2 screened plexiglass window for extra air movement on mild days in winter. How much vent space should I have per square foot of living space. Are wind activated roof vents preferable? If I'm using the deep litter method. How often should I turn and add new bedding/compost? I am open to all cost effective solutions for my flock of nearly 80 birds. Thank you to all problem solvers out there who can take the time to lend some words of wisdom. Prevention is the best medicine.