Thos Ammonia Filter Pad is a dense chemical filter pad which removes Ammonia from your aquarium water; effectively reducing the possibility of Ammonia poisoning. Ammonia Pads lower the risk of fish stress and disease while promoting crystal clear water. This media should be implemented as a preventative measure or treatment. Use a test kit to check Ammonia levels regularly. The Ammonia Pad is not a substitute for regularly scheduled aquarium maintenance. These Filter Pads can be cut and shaped to fit any filtration system, such as: Canister Filters, Hang-On Filters, Trickle Filters, Pond Filters, Wet/Dry Filters, Filter Cartridge Frames, and any other aquarium or pond filtration assembly. Great for both freshwater and marine applications. The pad measures 18" x 10".