2way pumps or pas through pump

Hello.. another weird question from me :
Where can i buy a pump that will pull or push? I need the option of hooking this to my computer...

or.. A pump that will let water flow through it (even though the pump is off).. the tubing would be going straight down.. so the only thing that would push it would be gravity.

any ideas?

thanks-Lee

Good ole centrifugal pumps are relatively free flowing when off.

WHAT THE HECK ARE YOU UP TO!!!

You gotta tell us! All this isn't for a girlscout bleach tank is it?