I made a DIY overflow with the continuous siphon. I am getting a bad gurgling sound from the overflow and a ton of bubbles in the sump. I drilled a hole in the tallest pipe. I started small and went bigger and bigger but it did not help. My overflow is a 3/4 inch pvc. I turned the pump up until the water level in the return section was steady. I have tried turning the pump down and up. When I turn it down I have lost siphon and my tank overfilled. Luck I caught it.