i think i know why some of u are having trouble with it the slot that hold the media are set up wrong instead of going right to left they should be up and down

the water comes out of the middle and then mover to the right

if u put 1 something in the filter that goes up and down( i use egg crates) u can fill the slot where the water comes out withe a sponge media and fill the far side with bio media and carbon the filter with get rid of more detus (poo) out of the water right away

u will kmow this works cause the water level on the closest side is higher the the bio media cause it get slowed down by the mechanical part

this will cause more of the water to get clean mechanically this is how my is set up from day 1 and might be wh y my water is clearer  

Mine came with no manuel just a picture sheet on how to set up.

Creamkiller,
I can't imagine what you are talking about.  The water comes up the intake tube which is in the middle of the two filter holders and comes over them equally and then through the bio-wheels and out back to the aquarium.  The media holder only will fit in the media holder slots...up and down.   Then the filter goes behind that blue fuzzy part towards wall or back of filter.
at least that is the directions mine shows that came with the filter.

My four Emperor 400 are only noisy when I restart it. After that it's all silent as a ghost.