Do you think the previous owner made his own GFI circuit?
Ocean Light T5 MH combo - Tips and Tricks
Always use a GFI when installing your lighting system
Use timers to create a consistent light cycle.
For easy HQI bulb installation, use a touch of white lithium grease on the bulb end-blades.
If your fixture includes daylight and 20K bulbs, use a separate timer for each color to simulate a dawn and dusk effect by having the 20Ks come on first and turn off last.
Installation inside canopies is not recommended and, without exceptional air circulation and ventilation, will shorten the life of internal components including the bulbs.
If you are upgrading to a more powerful lighting system, start the fixture higher above the tank and lower it gradually to within 6" - 12" from the water surface.