If you're going to be using pressurized CO2, & since you want high light, you might want to try two of the 3 bulb version of that Diamond Plate fixture:
http://www.homedepot.com/p/Lithonia...te-Fluorescent-Shop-Light-1243DP-RE/203300803 .. online shows it being black outside but I was just in my store a couple days ago & the display was chrome. Might have had black too but didn't check. The 3 bulb version is basically the 2 bulb one with a 3rd bulb added into the center that hangs a bit lower than the other bulbs.
My guess is two of the 2 bulb Diamond plate fixtures will give you closer to medium light except in the center where the light might overlap giving you a bit higher PAR. YMMV.
I have 1 single bulb t8 strip & one dual T8 Diamond Plate fixture (total of 3 bulbs) hanging about 24" & 27" above substrate on my 75 gal tank (only 18" deep) & I figured I'm low-medium but my setup is kind of weird. If my Diamond plate fixture was hanging lower the light would be too high on the back side of the tank without getting algae or using pressurized CO2.
If you find two of the 3-bulb fixtures are too much light check to see if you can disable one bulb & the fixture still operate correctly. Or you can use window screen or hang the fixture higher. Even the clear tube bulb protectors can cut the light just a bit .. not a lot though.
Nice thing about Home Depot, it's easy to return stuff.