im a smart indavid.that is how light reaches my grows.god gives me the strenght to do anything that has to do with my mind and thought and ideas.u ask how the light gets in.easy i say.go figure i say.mumble mumble i as well say.i just grow and no i grow ok.i have em positioned that the sun is always on em and the corragated plastic reflects 100 percent plus rays throughout my grow room.like a tunnel radient i guess du to corragation and sun all comes to affect.the sun dont have to hit directly on plants.if that would happen i would burn em in side a greenhouse with that kind of material without some kind of fans or exzaust.as now i dont need shit for greenhouse but me and me and me again