Go to your local hardware store and get some 4" flexible air ducts. Attach it to your tent, seal it off so its light proof, then outside of your tent just run it at a 90degree angle and you won't let any light in but you'll still have your airflow. If you really want to have no light in, put a 90deg bend on the inside and outside of your tent in opposite directions like a more straightened out Z. You'll get like the tiniest little spec of light through and thats about it.just want to know how important it is to block out light for lights off. I am low budget so i want to allow heat from the light (600whps) to vent without letting light in.