Planted Tank Enthusiast
Join Date: Feb 2012
Location: Edmonton, Alberta
Just a thought but all the aquarium canister filters I've ever seen work the same way, water is drawn in by siphon and flows through the filter via gravity and/or displacement from the siphon then goes into the pump for the return trip back to the tank.
The only canister filter I can think of that MIGHT work by pumping water IN is the API canister. I seem to recall that filter having it's pump inside the tank, but I don't remember if it's on the intake or the outflow.