whats the efficiency? dont say "just buy glass" because i got this plexiglass laying around and lots of it. so if i have a few grow boxes i wanna be able to use it if i can. and at the very least learn about it so i can let other people know. ive heard conflicting claims. one being that it blocks UV light. ive got it in my box now but i wanna know if it should keep it there. its going fine now but i cant know for sure if its hurting it all that much without doing some sort of experiment. if anyone has experience and/or knowledge pertaining to the efficiency of plexi-glass for a grow box please comment! thanks