Leak around return inlet fitting, proper fix?

[scrain]

Losing water at about an inch/day and I finally narrowed it down to a leak around this fitting. There's a gasket between the wall and the fitting, but it feels loose. You can see the leak in action here. I don't see any cracks when inspecting inside the return. I'm not sure if it's removable and a little nervous to twist on it much.

 

[1poolman1]

You can't twist the fitting, there is a pipe glued in on the other side of the wall. The fitting is tightened by a large nut, unfortunately also on the other side of the wall.
Could try a bead of an underwater epoxy around the flange until you can get access. JB Weld makes Water Weld for this type use.