Lemon juice works great. Just buy a couple of gallons worth at walmart and put it in a pump up sprayer. Spray the tent down real good inside and out and let the sun beat down on it for at least two day's. The mildew will be neuralized and your good to go. I learned this from a tent maker after completely losing a large wall tent to mildew. Looked like someone just shredded it into little strips.
