Brushless DC motor + submersible design: The pump motor is sealed and designed to operate underwater. Brushless motors are more efficient, more durable, and quieter than older brushed motors.
Screw / impeller mechanism: Many of these pumps use a screw‐type or multistage impeller design to generate enough pressure to lift water from depth.
Flow rate vs depth tradeoff: At full lift (close to 70 m), the flow rate will be lower than at shallower depths. Some specifications list ~1,800 to 2,500 litres/hour under good conditions.