I don't know much about that with soil to be honest....I'm pretty strictly hydro.
I glanced at the photo in your profile. I'm assuming that's mylar you have on your walls. As wrinkled as it is in those photos it may be causing some hot spots to your plants as well......just a thought. (on the whole your plants look very nice btw :thumbsup

Here is an excellent link to plant problems and how to fix them. Hope it helps.

International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!