1.PERFORMANCE - With a Max flow rate of 135GPH(500L/H), a Max lift of 2ft(0.6m) and 8W power, this fish filter is ideal for aquariums ranging from 10 - 40 gallons. If your tank is larger, we recommend purchasing 2 filters. Place one on each end of the tank for superior filtration! 2.SAFETY - Crafted with energy efficiency in mind, our aquarium filter features a permanent magnet rotor and a uniquely designed impeller. It's completely submersible thanks to an epoxy-sealed motor and each unit has been thoroughly tested in water under super high voltage to ensure it is from electrical leaks. 3.2-STAGE FILTRATION – Different from most of the internal filters in the market that only comes with a single density of coarse sponge, our 2-level filtration system works to keep your water clean and clear. (1) A coarse sponge filters out sizeable debris like food residue, fish waste, and plant leaves. (2) A fine sponge filter collects fine particles and impurities. Search code "B0D22PNSHQ" for the replacement sponges. 4.AERATING WATER - This fish tank filter includes air tubing and an air venturi to increase oxygen levels in your aquarium. Airflow is adjustable according to your needs. For adequate oxygenation, block the side water outlet while avoiding placing the pump too deep in the water.