#1 - Rio 2500 pumps are ticking time bombs. You need to replace it immediately with a safer pump. When (not if) it fails, it will fail spectacularly and will nuke your entire reef. The 2100 is just as dangerous, btw.

#2 - a 10g sump is very small, and there is virtually no linear travel time.

The flow through the sump should be 3x to 5x the volume of the display tank. If your tank is a 30g tank, 90 to 150gph is more than enough flow traveling through the sump.

The fact that your return pump sucks the return dry indicates that it is too powerful as well as the fact that the return section is too small.

Filter socks are fine if you set them up correctly. You don't want any part of the sock to be outside of the sump, because it will clog up with detritus and overflow. If the sock overflows, make sure it is situated so that it overflows INSIDE the sump and not all over the floor.

Socks should be swapped out every three days.