Esshops pf800 overflow issue?

[Alarsen77]

So I got a new sicce syncra 3 return pump that pushes 713 gph but should be about 500 at 4 1/2 ft head. My overflow is rated at 800 gph have it hanging on a 70 gallon marineland cube. Well if I have the pump running wide open or anywhere near it the tank will overflow the overflow doesn't seem to be draining anywhere near the 800 gph it's rated for any reason why help is greatly appreciated

 

[revhtree Verified Admin]

Bump for plumbing gurus!

 

[Alarsen77]

Thanks for the bump. I am wondering if it's the 90 degree elbow I have at the bottom of the pipe from the overflow

 

[revhtree Verified Admin]

Oh yea that very well could be the problem.