I agree on the MH
looks and growth.
The things is, IMO
it would be tuff to DIY a canopy for a MH
retro for a tank that small. The biggest issue with an enclosed canopy is heat. You can possibly just build a 4 sided box to fit over the frame of the tank with no top. Then you could mount a reflector with a MH
bulb centered over the tank. If you wanted to rip your old fixture apart, you can use at least the ballasts and buy IceCap retro T5 reflectors and mount 2 towards the front and 2 towards the back. Mount a computer fan on each side and you would probably
be good to go.
You would definitely have to light acclimate everything you put in there with that much light over a shallow tank. That would probably be too much light for some coral too.
If you really want MH
, you best bet just may be a new fixture, similar to this one