Reef Octopus Diablo DC 10500

[Hamsnacks]

Wondering if anyone else on here has one or maybe a similar model. Recently purchased one used and the seller really pushed how quite it was, but when I set it up, it definitely has a louder humming to it, a bit too much. Initially, I thought maybe cause it's connected directly to PVC pipe and I should replace it with a rubber hose but when I put it in a bucket of water with no connections I could still hear the humming noise.

Any suggestions, I did somewhat take it apart and it's super clean. Is my bucket test not the proper way to test it?

Any cheap DIY material I can put around it that would minimize the humming? Or should I find myself something else?

Thank you