is it 50% citric @ that make down concentration? I would like to try this because I already have it around.2 ounces for 30 bucks............you use 0.5mls for 16 ounces , enough to spray quite a bit of surface area.......the 2oz bottle makes 15 gallons. An easy choice for me....spend a little save a shitload. Does citric acid actually kill PM or is it a preventative that slows spread down. By the way, you grow a lot of great plants, good pics!