I see all the stuff that the sock collects (so I don't know about the comment that you won't see any difference). so if there is no sock, doesn't all that stuff just stay in the sump. becoming a nitrate factory? I highly doubt the skimmer bubbles can float larger items (meaning larger than a few hundred microns) up its neck to the collection cup. or can it? the sumps I have seen with no filter sock don't look as clean, specially those that run macroalgae, which essentially traps all the detritus and becoming a nitrate factory. sure they will eventually break down, but isn't it faster to "export" it every two days by changing the sock? I'm looking for a better reason not to use sock than just socks suck. for now, I see no reason not to use one.