White/Silver on Leaves

I started 13 seeds from 3 different companies and all of them have developed these white/silver spots/blotches on the bottom leaves. I don't know what this is or what to do. Please help. Thanks!

could look like PM (powdery mildew) could also just be lime from your water ? how is your humidity ?

http://www.growweedeasy.com/white-powdery-mildew

if you believe it is PM look in to H2O2

http://hubpages.com/hub/Hydrogen-Peroxide-for-Plants



also after harvest there is a solution to it

[video=youtube;S7jE7qzfgQs]http://www.youtube.com/watch?v=S7jE7qzfgQs[/video]