I have the same grow box you are using, are you only using 1 CFL?

I have gone with the 3 CFLs 100W 6000K setup with foil taped around the whole the inside. Though I know as per plans it should have 6 and I am working on getting that. . (The more light the better your grow)

Remember the food is much needed, and the sex of the plant could weigh on this with stress and PH and such.

hope this helps a bit