Frag tanks and coral grow out areas don’t need to be very shallow in order to get good growth. In fact, the shallower the tank, the more likely the coral is to get burned or experience photosaturation. With lighting technology as advanced as it is today, you can keep a very healthy and successful frag tank that is 16″ tall or more. You no longer need tanks less than a foot deep with energy zapping metal halides providing the illumination. Frankly, I’m actually tired of seeing 8″ tall frag tanks with halides over them. Just keep good water quality and ample amount of light and your corals will thrive in any shape aquarium.