Mounting external pumps upside down?

[Fish]

Hello,
I'm not sure if this is a DIY question, but I am sure that the people in the DIY forum are the right people to answer a question like this...

I am a little short on room in the stand under my tank but would like to put a closed loop through the bottom of the tank. Can I bolt my Iwaki pump udside down to the underside of the stand. Would there be any downsides to doing that? Would it adversly affect the pump?
Let me know if I didn't explain it clearly enough.

Thanks, Chad.