I Have Ordered The Eheim Pro 3 250

Hmm, check the spray bar holes cover each one up and see if the noise goes. Had a noise with my jbl spray bar and it turned out thatthe last whole of the spray bar wasnt big enough and the water was causing a whine as it came out. Widened the whole a tiny amount and the noise stopped.

Errrm....I have a really annoying hum.

It does not appear to come from the filter box itself, but sounds like some sort of resonance (spelling?)maybe from the Aquarium itself?

Interestingly it 98% disappears when I lift the lid flaps?

I cannot have the lid flaps up permanently and neither do I wish to listen to the hum..

I have tried doing all sorts of different things but to no avail.

The only thing that works is having the sprinkler bar out of the water with associated noise,which I do not dislike, and thousands of bubbles which I do not like.
!!
Maybe I am being too fussy

Any suggestions please?

Tanks with hums are starnge creatures. The 25 litre with the betta in has a lid consisting of a condensation tray and a sheet of perspex over that (cheap tank, original black lid cracked). Sometimes it hums loudly. The way to stop it is to move the perspex ¹/₄ inch. I have no idea how this stops the hum as the perspex doesn't touch the filter or heater wires.
The moral of the story is: if you have a hum, try wriggling everything; you'll be surprised at what can work 

Well the new filter is running well and no sign of the haziness I was getting with the Juwel, but to be honest when I swapped filters the haziness had all but disappeared.

Now a question for Eheim owners...how often do you clean your pre-filter out?? Don't want to do unneeded cleaning but I also want the filter to be running on top form.