You can light that tank with 1 MH
bulb in a Lumenarc reflector. You can use your current canopy, but you would have to cut a hole in the top so the top of the reflector can stick out. For full coverage, the bulb should be about 14"-15" above the water.
Analyzing Reflectors: Lumenbrite III, Lumenmax Elite, Lumenmax, and Lumenarc III
"The reflectors seem to fall into 2 separate groups, Group 1, the Lumenarc and the Lumenmax and Group 2 comprising Lumen Brite and Lumenmax Elite. The Group 1 reflectors seem to be better at providing a wider coverage, whereas the group 2 reflectors tend to focus the light slightly more creating higher peak values and smaller spread."
"The lumenarc III and the Lumenmax reflectors provide a large area of light coverage and hence are more suitable for tanks wider than 3 ft."
"The Lumenbrite and Lumenmax elite are more suitable for tanks 3ft or less in width. They tend to provide a more focused coverage and higher peak values than the Lumenmax and Lumenarc reflectors."