How to fix my noisy aquarium filter?

I just bought a 1200Lph Filer for my 50 Gal Tank. It is dead quiet when i am holding in submerged underwater in the middle of the tank, but as soon as i stick it to the gl on the side it starts to make a vibrating, rattling noise and it is very anoying because my fish tank is next to my bed. Is there a way i can fix this and why its happenins, Thanks