I have been using these Pinky filters as the top layer of the sump filtration in our 300 gallon freshwater aquarium for years now. The old filter material we used would tear apart after just a couple of weeks and need replacing. The pinky filter material retains its integrity until it is so full of detritus that I need to change it out before it starts blocking the flow of water (7 to 8 weeks). Such a huge improvement!