The Classic Bonded Filter pads feature an open fiber network that traps particles ranging from small to large. In contrast, the Premium Filter Pads combine layers: one for capturing small and large particles, and a dense bottom layer for fine particles. While Classic pads effectively clear most aquarium water and require less frequent rinsing and replacement, Premium pads deliver crystal-clear water by trapping more debris. However, this means they may need to be rinsed and changed more often. For aquarists prioritizing exceptional water clarity, the Premium True Dual Density Filter Pad is a popular choice.