The issue could have to do with the positioning of your air pump. It works at optimal level when it is above the water line, on a shelf above the tank for instance. To help, you could a strap a sponge to the underneath so it isn't directly touching the surface if the noise is due vibrations.

Make sure that the air line is secured will and that there are no blockages or things crushing the pipe.

You will also need to inspect the outlet connection point for any damages or obstructions.

If you find any damage to your air pump, or would like any further troubleshooting advice, please contact our customer services team who will be happy to assist you further.