YEE 6D Multi Layer Biological Filter Media Sponge (40*30*3.5) CM For Aquarium Filters and Koi Ponds | 5 Layer Filteration With Multi Wash and No Glue For Crystal Clear Water and Bacteria

Strong water purification ability Can be used repeatedly Cut to fit The yellow layer is facing up and the white layer is facing down. Establish a bacterial nitrification system. The activated carbon layer can adsorb a large amount of impurities.