Return Line Questions

[m109r]

Ok, so having recently finished my tank build, It seems I am constantly striving to improve my setup.....

Stats:
135g euro braced tank
33g sump
reeflo dart return pump
reeflo dart for closed loop with oceans motion
3 x lumen max elite hqi
Euro Reef 180
1/2 chiller

blah blah blah money pit.

I'm crazy obsessed with it, but I do however have a question about the return, after doing some additional research I'm finding out the restricting the return line is a big no no. However I cannot find a way to tune the return and supply from the sump....when I have the ball valve on the return all the way open it surges down, then breaks siphon, then starts the process all over again, not matter how I adjust the flow on the pump returning water to the tank

Drain line 1.5":


Return pump (front pump, from 1.5" to 1" )


I'm sure I'm missing something simple?

Or is that ok?

Any ideas?