Features: 1. Can be used in sea water tank, fresh water tank, aqua-plant tank. Suggested to clean it every month. 2. Cleaned once a month, no blocking, no deformation, can be reused after cleaning. On the cotton waste and feed residue, improve water quality filter clean. 3. The filter sponges are typically used as a pre-filter for wet/dry filters, sumps, and canister filters to clean water in freshwater, saltwater, reef aquariums and other types of fish tanks. 4. The aquarium sponge can filter out many particles in the aquarium or fish tank, avoiding residues and reducing the mortality of fish, which can increase the solubility of oxygen in water. 5. The sponge provides more surface area to catch the floating debris so that help to keep the aquarium water clear, which can also avoid debris blocking pump. Notice: *Actual color may be slightly different from the image due to different monitor and light effect *Please allow 1-3cm deviation due to manual measurement Description: Size:20*10*10cm includes: Choice 1: 1 pcs x Aquarium Filter Sponge Choice 2: 4 pcs x Aquarium Filter Sponge