Sicce 3.0 pump

[Hp1836]

So I have used sicce return pumps ever since I got into the hobby. The first a sicce 3.0 went about 2 years before it started vibrating very loudly at times. I cleaned it well and that did not help. It is connected to 6 inches of tubing then pvc. I also have it up off the bottom. The noise Seemed to happen at random times. so I replaced it.

The 2nd one lasted about a year before I started hearing the same loud vibrating noise for a few minutes here and there randomly. This time I contacted sicce. They sent a new impeller then a whole new pump. The new impeller did not help so I swapped out the whole pump. This time it took only about 3 weeks before I heard the same vibrating sound again. It's been on and off for a few minutes here and there a few times throughout the day. Strangly enough I hear it everytime I walk in front of the tank but it stops as soon as I get a few feet away

I am not sure what this could be at this point and have no idea why walking near the tank does anything. Does anyone have any ideas?

 

[aquaman67]

Is the pump sitting on anything shock adsorbing like neoprene ?

 

[Hp1836]

No it is hanging up not touching the bottom at all. When it gets loud I can see the whole section of tubing and pvc vibrating