The Girgle

If you can pull the end of your drain line just above the surface of the water in the sump. Thats what was causeing mine to gurgle. The air got trapped in the drain line and once it built up so much it rose to the top and gurgled.

http://home.everestkc.net/jrobertson57268/HGB/HGB_construction.html


This should help

I thought I did post it, But I may have forgot in the mist of all the other links I gave you...LOL

I was having trouble with gurgling in my overflow when I installed my new sump, and was constantly adjusting the ball valve on the return, because if I could get the water level high enough in the over flow it would not suck air into the vertical drilled pvc pipe, then I realised that it was because I had not set up the auto top off on the sump. Seems odd until you think about it, the sump is located a specific distance under the tank right, now the pumps flow rate reduces as the head hight increases, which is exactly what happens then evaporation occurs. So I stopped adjusting the return ball valve and started to increase the sump level more regularly with RO (need to get the auto top off done) and presto, as you increase the level, the head hight decreases and the level in the overflow increases and becomes stable.. If you add heaps of water, you can even move the level of water in your display tank to creap up above the weir.