Seachem Laboratories Mesh Filter Sock, sized 4×12 inches with a 250 Micron mesh, is essential for preserving aquarium water clarity. These socks effectively trap floating debris and waste, preventing the accumulation of harmful dissolved organics, nitrates, and phosphates. Incorporating Seachem Filter Socks into your sump or overflow system is vital for a healthy aquatic environment. Crafted from durable Polyester Mesh with secure stitching, this product ensures long-lasting performance.