white powdery mildew control??

I'm in my 5th week of flowering and am having some powdery mildew problems.. anyone know how i can get rid of this??

I recommend Green Cure, it got me through harvest. I also tried serenade, but the smell drove my roomate crazy. heres a good article about mildew http://urbangardenmagazine.com/2009/08/how-to-beat-powdery-mildew-in-hydroponics/

Ed Rosenthal's Zero Tolerance Herbal Fungacide helps, neem oil also helps,
as well as milk... anything to help bring the pH down really...

I've been using Fungus Pharm seems to be working great, just need to spray about every 4 to 5 days.