Something else to consider is when you switch on those air cooled lights, all the bends in your duct work from light to light will restrict airflow by 20% for each bend.
I see you are currently running what looks like a light wave t5 at present
Have you switched on your hid lighting and tested temps yet?
IMO remove the bends and straighten the duct work from light to light to try and get a straight shot through each of your reflectors.
I used to use a 600w with blockbuster hood and my plants could touch the glass, however I experienced light bleaching from it.
After that I kept it at least 6" away.
J