Cooling- sump vs hood

My clip on fan just quit on me. It is one of those student clip on types.
It was clipped on to a riser pipe pointing to the back of my aquarium hood.
Underneath the hood I have ~ 650 watts of lighting in the PC/Halide flavor.
Using this setup I have been able to maintain 78 degrees F.

I have just recently added a custom sump. I got the inspiration to build
this after looking at Marc's site. Seeing that I now have the sump, can I
get away with just putting a fan underneath the stand blowing into the sump
for my cooling
needs? Is there a negative effect on bulb life if I choose not to add fan
cooling to my hood?

tia