Noisy Gurgling Overflow - SOLVED!!!!

[Ron99]

I actually have a reverse Durso at the bottom so air can escape. No back pressure in the line and it is not flushing or siphoning at all. It's not an air gurgling sound but a constant loud sound of the water flowing/rushing down the pipe. I do have an adjustable air valve in the cap at the top but changing that does nothing for the noise. It only changes the depth of water in the overflow box.

I have pretty much come to the conclusion that trying to run a single external Durso overflow from a bulkhead on the back of the tank near the top is extremely difficult and a poor choice. The best way to run overflows drilled at the top back of a tank is the herbie style. I am going to see if I can come up with a clever external herbie run off one bulkhead.