Not at all, kelvins is a factor though. 6500K is too low on the spectrum for reefs, those would be usable in a planted tank though.
W/G isn't a very good measure of how much light/what kind of corals you can keep, it's measured by PAR which isn't a very easy-to-obtain measurement. Just look at LEDs, very low wattage but when used correctly (And the right type of LEDs) they can be as strong or stronger than any T5HO or MH fixture.
What you're looking for is Kelvin ratings in the 100000K-200000K range for reefs, but being able to keep your hood probably won't be an option. I assume you have one of those generic hoods with 2 screw-in sockets?
Something like
this one or
this one would be perfect for you