By grow lights do you mena those flourescent fixtures you get at the hardware store? If so, then yes, you can use them (actualy I'm using one of those over my 45g right now), just you'll want to replace the bulbs and you'll need roughly 4 6 foot bulbs just to keep soft corals... 6-8 for LPS... 10-12 for SPS. But using standard shoplites, I doubt you'll be able to fit more than 6 bulbs in there. If your looking into high light corals, it would be a good idea to switch the balasts and bulbs out with VHO's.
But more than likely metal halide pendants will end up being cheaper in the long run if you are planning to keep high light corals.
