I have a 50 gallon PNP system. I have a durso overflow which continues to make an annoying sucking noise where the air vent is. I believe the reason is that the water level Is equal to the air vent, causing the water to making a sucking noise into the air vent. Any idea how to fix this or how I would lower the the water level in my overflow. Keep in mind I have no valves in my sump. Attached is a video of the sound the durso pipe is making. Thank you!