Have you looked into a SOG grow. That is the way for you since you don't have much height. Just remember at times you may need 24inch clearance from that bulb. That tray is probably going to be higher than the res. to prevent all the water syphoning out of the res. so u may run into some height issues. Figure the light to hang down atleast a foot, and your plants in pots on top of the tray on the res are going to be two feet aprox, and now light clearance, that leaves you with enuf room to gro your plants 1/2ft tall. Have you thought about a DWC setup. That will save you a few more inches since you grow right out of the res. You could also look into T5's, these are just as good for veg, but u lose a little in flowering, but in your case you would make out better since you can grow plants right under the bulbs(even if they touch its no biggie). This will also save you a couple more inches. Which will be a lot of bud when you multiply it by 30 ft squared