I'm surprised no one has asked, what kind of fish do you have?
Some fish require different flow rates and current . With 2 X 2" overflows you have any number of options, whether you have a 20 gal sump or 200 gal, The overflows, and pump size are physical determiners here, but the fish are most important.
Fish from fast flowing rivers require a higher oxygen saturation, which is provided by current, cascading water, and riffles.
If, for example you have bettas or anabantids, or other slow water species a small pump is all that is needed.
If you have Tomocichla or Chuco genus cichlids the current should be high.
Most aquarists keep something in between.
I keep Tomocichla seiboldi and asfraci which should be given highly oxygenated water to be healthy, on the asfraci tank (a150 gal) I use a 2400gph hour pump, with venturi tubes attached.
The young seiboldi are growing out in a 75 gal with about 1200 gph and venturis.
I also find current has tendency to curb aggression in faster flowing waters with these kinds of fish.