Yeah my bta prop tank is under t5s, but a gigantea is much different. I had a h. mag under t5 but it moved too much looking for more light. With metal halide, the light isn't spread out as evenly, so they stay put for the most part.
Thanks for the opinions so far.
Now I am going to track down a blue gigantea to go in there, but if he doesn't seem happy, he will be relocated.