First of all, never set your air pump on the floor as in this picture.
If the power fails the nutrient could siphon back into the pump.
Then of course when the power came back on, the pump would fail.
This is a very simple and forgiving type of growing, especially if using rock wool or a high-water retention medium because there is only one component that might fail under normal conditions and that is the air pump.
This could give you many hours or even days before needing to replace or repair the pump if it fails.
However, I would personally never recommend that any type of reservoir be without an air pump and at least one air stone to keep as much oxygen in the nutrient solution as possible at all times. Without enough oxygen, plant roots die and soon the entire plant will be gone.
This type of system can be set up in a bucket, table or trays of almost any kind.
It can be used with most type of mediums as well and is a very simple and easily maintained system.
Many commercial growers use this system as a raft type system where plants are floated in the nutrient solution held there by usually Styrofoam rafts.
Highly oxygenated nutrient solution is a must because the plant roots are totally or at least partially submerged.