I have a drilled 180 with 1 and 1/4 inch lines draining to my sump(55 gallon)I have the drain lines draining into one compartment and then overflows at the top to the bio ball chamber..Anyways the lines bringing water to the first chamber have air in them also which creates loud bubbling ,I have since put a filter at the end of both lines to reduce the size of the bubbles so its not as loud...Now grant it with the doors closed on my stand its barely audible,but I wanted to know if there is a way to not introduce air into the sump and stop the gurgling completely???I thought I read somewhere someone used a ball valve and gated it down and reduced the bubbling but I cant figure out how that would do anything.I dont want to slow down my turnover rate....Im using tubing for the lines ,its not hard pvc setup....
That set up is basicly a syphon rather than a standpipe design that works as a drain and won't draw in any air so they work a LOT quieter.