flow and pump/overflow

[fishguyxd]

I have a mag 9.5 on my 72 gal (3/4 line from pump) and from overflow it is (1 inch line). When I open the valve full or any over half from pump and try to get the overflow line to get a match of outflow (so water does not do a gurgle sound thing) it never seems to be able to match up and to say a best the valves are tight. I am afraid it might snap of at the bulkhead and glass area. is there a way or procedure I should do? currently it does not make any sound other than when it's time to topoff
but i am just trying to get more flow.