those fixtures are waaayyy to big unless you have a humongo tank and want to hang them from the ceiling... even then they look like a little much...
those look like industrial lights (I.E yellow light <=6500k)
if i were you i would try to remove the socket, wiring, and ballast.
Then re-wire it, and make your own reflector or purchase one.
then, buy bulbs that will fit your needs.... REEF TANK >= 10,000k