Okay, next idea. Reduce both drains to 1" pipe with a reducer on each drain at the overflows on the display. Separate the drains and have both terminate below the water line in the sump. If that doesn't work.. call in the big guns.

Sorry I just re read this. For a basement sump you pretty much need to have the drain valves downstairs. What happens is the water drains into the sump and causes water from the sump to be sucked back up into the pipe until that column of water becomes too heavy and dumps back into the sump. this explains the surging you're experiencing. I would try separating the drains, gate valve one of them at the sump so that one is a full syphon with no air intake at all, terminating below the sump water line. That's all I can think of.

So I have done this and it has been running pretty good for over 24 hours now!

Awesome. You have a great set up. Will be following along for sure.

Of course as soon as I posted this I had my water level drop down somehow in the display, which took a tiny closing of the gate valve and everything has been good for 18 hours or so now. Maybe me adding a filter sock onto the drain line in the sump yesterday...

Thanks for your support brotherd I appreciate the responses on my plumbing setup.

Hopefully shortly I will find out what camera I should be investing in to get some good pictures of my tanks contents. I got a really nice majestic anemone that my clowns are loving and about $800 in new corals in the past month or so that I would glady show off once I have a camera worth doing so with.

Cheers for now