The filter sock should be the very first thing the water touches when it gets into your sump. Im not sure why you put yours in the middle. The filter sock will do an excellent job of mech filtration. If you put a pre filter on your overflow it'll be even better. the way you have it now it looks like the water isnt being filtered before it gets to the bio balls and your bio balls will end up with a lot of dirt and debris on them. That's not good. I would take out the bio balls under that first section and put in a big filter sock and sock holder into that section. Then put your filter pads underneath that or around it to catch extra waste.
