Is this good flow?

[Patx]

The return placement look "not enough high".
Maybe you should test what happen if the check valve don't close.
If sump could handle the water...

 

[PotatoPig]

I didnt want to use one at all but many people convinced me with the height of my return and my sump size I had to run one. Anyway its fixed now and man that water is scooting out!

Safest option is to have the return just below the surface and have enough spare capacity in the sump that the siphon will hit air in the DT before the sump overflows.

Check valves… if you’re relying on this and it fails you’re looking at possibly thousands, maybe tens of thousands, of dollars damage.

 

[AquaForge]

Safest option is to have the return just below the surface and have enough spare capacity in the sump that the siphon will hit air in the DT before the sump overflows.

Check valves… if you’re relying on this and it fails you’re looking at possibly thousands, maybe tens of thousands, of dollars damage.

This has been an issue since I was told to drill it where it is (found out after its too low). So,did some math and the sump "could" handle the 3" inches of display but I would rather not find out the hard way. I did come up with a nice 90 Street connection but people said it looked too complicated and to take it out. I will attach a pic of that contraption. It DID raise the water line to the bottom of the input to the weir so maybe I should put it back.

 

[The_Paradox]

90 is a big number. Angles… yup. Too complicated for a lot of people here.