The quietest aquarium air pumps typically have the following characteristics:

Sound insulation design: These air pumps typically adopt sound insulation design, including noise damping materials and structures, to reduce vibration and noise transmission during operation.

Low power motors: Low power motors typically generate less noise. Some quiet air pumps use energy-saving motors, which are both quiet and can reduce energy consumption.

Acoustic isolation: Some advanced aquarium air pumps use acoustic isolation technology to minimize vibration and noise, making their operation almost silent.

Mute accessories: Some quiet aquarium air pumps come with mute accessories, such as mute bubble stones or mute air pump kits, to help reduce noise during bubble generation.

Adjustable airflow: Some models have adjustable airflow function, which allows you to reduce airflow as needed, thereby reducing noise.

High quality materials: Aquarium air pumps made from high-quality materials are usually more reliable and have lower noise levels.

To find the quietest aquarium air pump, you can choose from the following methods:

Product reviews and reviews: Check the product reviews and reviews of other aquarium enthusiasts to understand which air pumps are considered the quietest.

Consulting professionals: Consult the staff or professionals of the aquarium, who may provide you with advice on quiet aquarium air pumps.

Brands: Some brands are known for their quiet air pumps, and their products can be considered.

Cost: Generally speaking, higher priced air pumps may use more advanced sound insulation technology, but quiet air pumps with higher cost-effectiveness can also be found.

Please note that even quiet aquarium air pumps may produce slight noise after prolonged operation. If you are very sensitive to noise, you can consider placing the aquarium in a place that will not be disturbed by noise.