This is the golden rule. The pump should sit on top of your tank hood, stand, or a shelf higher than the water surface. If placed below the tank and the power goes out, water can siphon back into the pump, destroying the diaphragm.
For the DIY aquarist, the is a modder’s dream. Kd-a180 Aquarium Air Pump -
: Operates at a low power consumption of approximately 2.5W , making it an economical choice for continuous 24/7 operation. This is the golden rule