1. remove the 4" tube and just hang it on the drain pipe with a string or make a holder a couple inch below the rim of the sump and let it sits on the holder only. this will increases the flow through the socks and you could see if it dirty ect..
2. take out the filter pad on top of the drip tray. this will increases your flow evenly over the sponges. your socks and the filter before the pump are enough.
3. your pump intake is on the high side. you may need to raise the water level in your sump to stop it from sucking in air but this means you will have less room in your sump once the power is out. If there is a power outage make sure their is room for the water drain down from your tank and not overflow your sump.
On my tank i have a 90 gal sump with the pump intake is at 1" from the bottom. i keep it 35% filled with water during running. once the power is out it will fill it to 75% with water. Just something to think of when you install or drill your overflow, if its too low then there will be too much water drain down once the power is out...