Jtang,
I dont know if it will help, as its not DIY, but here are two solutions that I have seen to the problem of a hex tank-
1- you may want to look for a metal halide pendant style light- go for a 10,000K bulb, and you should get good coral color.
2- go for an icecap ballast, and you should be able to fit at least 3 bulbs accrost the center of the tank. I know someone who did a 35 gal hex that way, and then made a coral mound in the center of the tank, attaced to a PVC framework. It looks great, and the corals are doing very well near the top.
Feather dusters and other critters make up the lower sections of the mound.
Gene
------------------
" To laugh often and much, To win the respect of inteligent people and the affection of children, To earn the appreciation of honest critics and endure the betrayal of false friends, To appreciate beauty, to find the best in others, To leave the world a bit better, whether by a healthy child, a garden patch or a redeemed social condition, To know one life has breathed easier because you have lived."
THIS IS TO HAVE SUCCEEDED
Ralph Waldo Emerson