Noise from this product can be caused by two things; priming issues or impeller issues.
Priming issues with hang-on filters are easily solved, the filter will need filling with water from your aquarium before they are turned on. You may also need to top your tank up to ensure that there are no problems moving water from the tank into the filter.
If this fails to solve your issue, check the impeller to make sure it is not damaged or dislodged at all. Please remove the impeller and check that the propeller fan piece is attached to the magnet body and it is not split.
If this does not solve your issue, please forward any images of damage to our customer services team to help them further assist you.
Important: Disconnect mains electricity supply before handling or attempting maintenance. Always fully read and check the troubleshooting section within your product instruction manual.