The glug is where the water comes out of the overflow pipe in the sump. The overflow up top is quite quiet. I did try moving the air line up & down, but not a lot, was kinda in a hurry by then. I agree some times thing run better/smoother after awhile.
As much as I thought about all this. I still missed a valve to shutoff water to the return pump, for when I need to clean pump/check valve. Have one coming wed, so it can run with freshwater till then anyway.
It is really cool that I made every thing so it can come apart if need be. I even have it so I can disconnect the overflow & return pump & remove the tank & top (with water) from the stand. Hope I never need to though, because that would mean some thing had gone very wrong in the sump area. It makes it easy at this point though because I can take it all apart when it's time to move it upstairs.