Need a bigger sump?

[clancaster23]

I just got my 180 gallon filled with regular water for the first time to do a leak test and basic plumbing test. I have a 30 gallon sump underneath that has three compartments in it. The left should be the fuge part, center is where the return pump is and the right is where the skimmer would be. This tank will use a closed loop system with a custom built overflow covering two 2" overflow pipes inside, one up, one down. I have durso standpipes on both. I am using a mag drive 2400 for the return pump. My problem now is when I turn on the pump, water flows through the system fine but the water basically comes gushing down only the right return hose (the pipe facing down) since the water level in the overflow box doesn't get high enough to get water in the other side, the one facing up. As the water comes down out of the hose, it quickly fills that side and rushes over the wall into the pump section with basically too much flow and causes a bunch of air to go in the pump and it's forced to shut off.

I'm basically looking for something to reduce the amount of flow coming out of the hose from the overflow without reducing the output of the pump since I need the flow because of the closed loop system. I was just thinking maybe I can get some kind of double splitter and make that one hose into two and then I'd have the one hose split off to each end and that would cut the plow in half and get water to each side of the tank like I need.

I do have my old 40 gallon breeder that I might be able to fit under there but I'm not sure if a bigger sump would solve the problem.