^not good. If you are going to use an external pump, then you should drill a hole in the sump.
If you had the pump mounted below the sump, then you could get a siphon going to feed it, but in all reality... you should drill a hole in that sump.
it's easy...
www.glass-holes.com
http://www.youtube.com/watch?v=GSYqSeW1mQg
The only thing I'd suggest differently than the video above is to use duct tape on the inside of the tank when drilling so that the glass hole doesn't pop through and crack all over the place and potentially cracking the other side of the tank.
Sump looks great though and I am going to copy your schematics and just size it down to my needs. thanks for sharing.