so your tank drains into the skimmer section, then is pumped into the fuge, and overflows into the return pump section?
your using 1 too many pumps. you dont need the pump to get water from the skimmer section to the fuge. you can use the same overflow idea that yuor using to get from the fuge to the return area, and eliminate the fuge pump. just seperate the skimmer area and the fuge with a bubble trap to keep micro bubbles from making it into the return zone. you dont want bubbles making it back into the display tank.