In addition to what the other people said, you should also move your intake fan to the bottom of the grow cabinet, and get rid of the foil... Just paint the inside white.
It's much more reflective than foil.

Good luck with your widows, I vegged my last WW for about 2 weeks, and switched to 12/12 at that time... The plant was about 5 inches tall (not sure what that is in cm)...
By the time I harvested her, she was 2 feet tall...
dooobster Reviewed by dooobster on . growing white widow I am starting my first grow, i have chosen white widow seeds for this. can someone please adivse on light cycles, ph values of water, nutrient levels to add, and at which times. when to change the light to bud. i have crafted a tall cupboard for my grow room, covered it with the dull side of tin foil (in order to stop sun spots, so i have been told). I have two fans, one bringing air in from the top, which is vented right down to the plants, and one at the top venting air out. i then have a Rating: 5