Is it brand new or been around awhile?
If it has been around awhile, sometimes something gets stuck like a MTS snail. If it is brand new then sometimes there could be something from manufacturing in there making noise or it could be faulty.
Is there a motor you can take of with the impeller inside and open it clean it out and put it back?
Also if it is new, I would just return it if taking it apart and putting it back doesn't work.