Hi there.
I had an indoor orchid house that I used artificial grow lights in. Frankly, your aquarium light, if it is a "grow" light may be exactly what you want. I was growing "low light" orchids and they still required a lot more light than I imagined. I suggest you learn more about plant lighting. I have put one link below to get you started. There is information about about individual plant needs online.
Also, if you have a friend who is a photographer they may have a "light meter" so you can measure the light put out by your aquarium light. Another piece of useful information is that artificial lights disapate quickly over distance, even a foot or two, so at the top of the aquarium it may be full sun and the bottom full shade. Just some things to think about.
Add a heater and you can put in miniature orchids and I have a pet frog in mine!
Dee

Here is a link that might be useful: Houseplant light requirements

Heck, even without a heater there are plenty of orchids that would do just fine. As Dee mentioned, your current lights may be an excellant lightsource. Did you have corals in your tank?

Obviously, the tank would have to be very well cleaned out in order to rinse away as much salt residue as possible. On the plus side -- the possibilities with that size tank! I envy you!

After cleaning, you should try and consider just what kind of terr you would like to have as well as how much maintenance you are willing to do. This will help to focus your search for plants as well as other decor or themes you might use.

Hi
I converted my 150 into a terrarium after hurricane frances tipped it over lol. I sold my lights and equipment as that's WAY more light than you need for a terrarium. You should be able to get enough money to pay for the setup!!! good luck gary