Why is my wet dry gurgling???

Is the durso the L shaped pipe in the overflow, turned down that drains the water? If so, I don't think drilling holes will help because it's all above water if I don't restrict flow. I'll upload a drawing in a sec.

 

half of the durso should be out of the water

 

like this.

 

Hmm, here's what mine looks like. And I'm trying to balance it go cover half the durso, but it's draining below the mouth of the durso faster than the pump can pump the water back up:

 

you cant be draining water faster than its gettting pumped in. its impossible.

you have to mess with the air hole to get the right amount of air going in.
what size tank? and whats your return pump? the pump size might be the issue too.

 

Ah, i did see an air tube, I'll have to mess with that later when I'm home. And that's what I thought initially, it will drain as fast as it's pumped in, so the tube must have too powerful suction (and the air tube controls this? If so, wouldn't that be the same as restricting the size of the drain tube, what if you cut down suction too much?). The pump is decent but i'm not sure about gph. It's a ~40 gallon, btw.