Silence 1073.040 Unbelievable Loud

[VeL]

Six months ago I purchased this pump brand new for my future 120g which is now ready. A week ago I installed it as a return and I could not believe the noise that is coming out of it. It makes a constant grinding sound "rrrrrrr", vibration like. I made sure it does not touch anything but the bottom of the sump by the suction feet and is connected to a silicone tubing, so it cannot be from vibration. I read on the web that these pumps get loud when used as returns so I switched it with an old 1260.
Now the pump is installed as a feed pump for my GFO / Carbon / Bio Pellets reactors, set at the lowest setting. For my surprise it is even louder. It sounds like the impeller is grinding / rattling / out of ballance. It is under the cabinet and with the doors closed I can still hear it 10 feet away. For comparison I hear the pump clearly even when my two vortech mp40 pumps are at full power and we all know how loud they can be. I opened the pump and everything looks fine, it is completely clean as it has been used for like 9 days total. Maybe I am missing something, maybe something inside got detached? Any suggestions will be greatly appreciated. It is sad that a new pump from a reputable brand advertised as silent is at least 5 times more loud than a cheapo chinesse pump :deadhorse1:

[rvitko]

If the bushings on each end are installed correctly in the pump and impeller cover and the shaft is not broken, the only other possibility is that the shaft or ceramic bushings have some chip or crack, please check these carefully. The pump should be about the same noise as an Eheim 1260 for example, not more.

[VeL]

Thanks rvitko, unfortunatelly the Silence is like 10 times louder, the Eheim only makes a low humming sound. I do not want to sound like Tunze non-fan as most of the stuff in my two aquariums are Tunze - osmolators, pumps etc., but this particular pump is driving me nuts, even when I am watching tv in the room - I just hear it on top of everything.
Anyhow I will detach it from the reactors tomorrow when I wake up and do a close inspection. I really really really hope that something is not installed corrently and is the reason to be so loud.

[rvitko]

It is not a loud pump, something has to be wrong with the drive unit for sure.