Diameter of return pipe

[dela]

I've got an oceanic 90 gallon reef ready bowfront tank. It's got the built-in overflow in the middle. I'd like to replace the return tube with a new tube that feeds a SCWD within the overflow chamber. But I have no idea what size the tube is. Does anyone know what the diameter of that tube is? I seem to recall it was a thinner PVC pipe. It was not the normal schedule 40 pipe.

I'd rather not take it apart until I'm ready to install the new one.

Also, has anyone attached 90 degree elbows to a SCWD. I assume this is fine and does not create any issues with the device? (I've heard they can start clicking).

Thanks

Mark