I recently bought an eheim, and man is it quiet. I bought it because i was changing everything in my tank going for silence. I have to say the first day though, i was happy with it, but a little disappointed because everyone says theyre "silent". The first night it was on, it was making a little noise, but when i came home from work the next day it had gotten much quieter. Now theres no vibration at all, only the slight sound of water running through it. If you bought it new from the store, i would give it a day to settle down. Also, when i open it for cleaning, if i dont open the valves and let all the water run in and the air run out of the output valve, after turning it on it makes a little noise for a while.