Need help with a noisy sump problem

[shanev]

Here the lineup I have a 29 drilled with a 1" overflow in a corner overflow box with a durso standpipe. I have a 10 gallon sump/refugium in the stand beneath it.
For plumbing to sump I have all 1" PVC (non-flexable) it comes stratight down then makes a 90" then I have a T pointing down to go into the sump. Beyond the T is a 1" Ball vavle then then it
extends to a 90 going into the refugium.
Returned to a spraybar via a Mag 7.
Now the noise I get is a gurguling sound where the water enters the sump. It is obviously getting some air in the way down via the hole in the durso.
Any ideas on how to stop the gurguling?

 

[shanev]

Heres an image to help get an idea of what Im talking about. Right now Im leaning towards the 90 at the bottom of the overflow line is creating too much turbulance causes more air than necessary to be pulled in through the durso air hole.
Any ideas?

 

[jester]

I had posted a topic several months ago on how to quiet sumps. Do a search on my posts and it should come up. In short, I used several 45 deg stree elbows in such a mannor that it is about 4 in under water line of sump.
My plumbing is 2in at that point, but I suppose it should work for your setup. Also, do you have a ball valve on your return line?