I don't remember what my pump was rated for, but it was more than necessary for 1/8" tubing. I used a home built PWM motor speed control to run it at around 50%. Still sufficient flow and dropped the current in half. If the pump is a gear type with close tolerances then I suspect a blockage (or small diameter tubing) would cause the current draw to rise and might even stall it. An impeller type does not.