The tank I inherited came with a filter sock on the sump return. However, it did not come with a lesson on how to use the filter socks. How often should I clean them and how should I clean them? How many times can a filter sock be used before it has to be replaced? Is it necessary to sterilize the filter sock every time you clean it and, if so, what is the best way to sterilize? My tank is running pretty high nitrates and I've observed quite a bit of detritus buildup in my sump. The sock seems to foul up pretty quickly, and the bottom of the sump has a layer of detritus. I'm going to get on a schedule to clean the detritus out of the sump weekly when I do a water change, but it seems the filter sock probably won't go very long without cleaning. Finally, my LFS recommended I put porous rock media inside the filter sock, which I've done, to support the development of bacteria to reduce nitrate. However, it seems to me that this porous rock probably creates more problems by blocking off part of the filter.