I fully agree with the debris floating in the water column comment, but I have to say, I love the growth and health I see.
And the reason they can be 'nitrate factories' is because someone mentions 'after 4 or 5 days etc, etc'.
Well all that gunk, food, etc, that's been sitting there for 4 or 5 days, has been decaying. And during that whole time, nothing has been able to get in the sock, at the food, to eat it. So yes, it will just decay.
I'm fairly positive these would not survive if I had filter socks.. I also don't have any surface skimming heh.. (lookup Tunze 9001 modes, the recirculating one to preserve plankton)
Tunicates, sponges, crinoids.. The sexy shrimp was actually eating debris that was floating on the top of the water that day. And I've never seen as many, and as big of pods that I'm seeing about a year and a half after removal of mechanical filtration. The sps aren't the only exciting thing in my tank anymore...