Isn't it somewhere in the area of the intake tube?
The Emperor 280 IMO
is too weak for your 46 bow. I have this strange rule of thumb thing for myself, that the water flow of the filters should add up to tank capacity x 10.
of course it won't go so well on larger tanks but I don't plan on getting larger tanks...
for example, 30 gallon tank: 300GPH total flow. For my 38 gallon I am getting, thats 380, which I am going up to 400 on a emperor 400 or a hagen AC50 paired together or with another 200GPH filter.
Rena FilStar xP3, Aquarium Systems Visi-Therm 200W (2), Coralife 48" Aqualight 260W 6700K
10 Gallon Hexagon
Hagen AquaClear 30, Visi-Therm Deluxe 50, DIY CF 20W 6500K CF, Hagen Natural CO2 System :: Bloodfin Tetra (1), Red-eye Tetra (3), Black Skirt Tetra (3), Harlequin Rasbora (6), Platy (1), Otocinclus Catfish (1) :: Rotala Indica, Hygrophila Difformis (Wisteria), Cabomba Carolinia