Gurgling sound on intake bulkhead

[tHeHEYzeus]

Hi, I'm putting together a new tank and was having trouble getting rid of a gurgling sound from my intake bulkhead. I was going to set up a raised loop thing with pipe behind the aquarium but I can't think of the name of it, it kind of looks like this

..............hole-->
..................___U___
Bulkhead.___/ ........\___ Sump

...................^PIPE^

Sorry for the rough sketch was hoping that someone would know of a link that explains how to do it.

Thanks for any help

Tank.jpg