Nothing more than a full moons light. Still better to not have any at all. Cover it with a cloth as said before.
i use the foil dryer vent and bend it up and around no light gets in!
here's mine first two are the inside of my flowering room and the others are the vents into the vegging room bootleg with the duct tape but it works greatSo heres how I solved it.. simple no cost.. lol and I got in the tent last nite with just the veg box lights on, and I couldnt see anything.. nothing nada.. it was great lol
here's mine first two are the inside of my flowering room and the others are the vents into the vegging room bootleg with the duct tape but it works greatand a bud shot for luck