75g tank and diy 40b sump test run issues

[scrappy35]

equipment:
40b sump with about 10g worth of water storage for when pump is off
eshopps eclipse m overflow (drilled and suppose to be 800gph)
hydor seltz d 1600 gph return pump with 6 settings.
All 1” pvc

Problem 1: with the pump on the second to lowest setting, the back overflow box will flood if I block the main return and rely on the secondary return. On the lowest setting, it just gets by. Do I have something wrong in my plumbing? Should I have the emergency drain above water level?

Problem 2: this overflow is loud on the tank side. I was attempting to adjust the water level and emergency stand pipe to quiet it down when I realized it is all but too high in its factory condition to not flood if the primary were to get clogged. Any ideas to quiet the waterfall effect and not flood at the same time?

If the settings on the pump are linear ( which I’m sure they are not) then each setting should be about 260 gph at zero head, which would make setting 2 520, well within the limits of the overflow box.
Happy to get more pics, video or answer any questions to clear things up if need be.

I have pics, but will have to figure out how to post them.
Thanks
Shane

 

[scrappy35]

Here’s the pics

 

[scrappy35]

I also shortened my overflow pipes into the sump, but I just came across a post that said no longer than an inch, preferably 1/2”. I think I am closer to 2. I can try shortening the backup side and see if that helps.