noisey wet dry filter system

[hoppertoo]

I just bought a new wet dry system for my 55 gallon and i was woundering if anybody could tell me how to get rid of the gurgling noise coming from the prefilter area.the noise comes and go's.also does the hose from the bottom of the prefilter to the top of the wet dry have to be straight down or can it have a loop that go's down and then up again.
Thank you for any info.

 

[the rock]

the rock says...
agree with RR, unfortunately sometimes that is difficult to do, but you just simply need to spot the problem and figure out how to fix it appropriately

 

[seamore]

seamore concurs