Filter Bags hold different types of filter media that help with water filtration. For example, Aquarium Filter Bags can be used to contain activated carbon, which helps remove harmful chemicals and toxins from the water. They can also hold bioballs, which provide space for beneficial bacteria that break down waste. Filter Mesh Bags are useful for holding various media like sponges or ceramic rings, which help with mechanical filtration by trapping dirt. Using these bags keeps your filter media organised and ensures your aquarium stays healthy for your fish.