Ah same bulbs im using, if the humidity is higher than 30 and temps lower than 82f try for 15-20" (you could try lower but im not going to take blame incase it actually does cause light bleaching) from tops just for 2-3 weeks from 12/12. Ive gone 10" from my tops before with afghani's with a 1k with no bad effects. Air cooled hood of course.