Filter socks are often used in saltwater tanks to keep the water column free of particles so your water looks crystal clear. If you change and clean your filter socks regularly, they can be a component of your nutrient export maintenance cycle. Most reefers use the felt filter sock on the output of their overflow pipes so the water leaving the tank has to pass through. The felt-like filter material will catch food, fish poop and particulate matter. This will stop the material from being recirculated back into the tank. If you are diligent about swapping these out, you can avoid the release of nitrate and phosphate that is made from the organic matter in the filter sock. Filter socks come in mesh or felt and with draw strings or plastic rings. Vertex and CPR Aquatics make holders for the plastic ring filter socks. The mesh filter socks are more commonly used for media filtration like carbon and GFO. However, the mesh can be used to capture large particles like whole fish food pellets or shrimp. So how do you use filter socks? Tell us about it in the comments below.