floating particles

[mark]

If not sand or micro bubbles then detritus.

Assuming the sock are reasonably fine (am running 100 microns that work)and not overflowing they should eventually get everything.

[wickedfrags]

I have a very similar system also pulling 2000GPH through my 4' sump, and with an external skimmer. The 100 micron bags I use do a great job and keep the water crystal clear.