Laguna PowerFlo External Biological Filter 1000 is ideal for larger ponds up to 1000 US gallons (4500L). The filter features an efficient 3-tiered filtering system that provides complete mechanical and biological filtration. The top tray houses pumice filter material (included) which provides mechanical and biological filtration. Below the top tray, a foam pad (also included) performs mechanical filtration. The bottom tray is designed to hold the biological media of your choice, such as Laguna Bio-Max(not included). The trays have convenient handles which allow you to remove them easily. Other features include a built-in drain plug and two outlets for creating waterfalls or connecting to other pond equipment such as a UV Sterilizer. The filter is designed to be installed outside the pond, which allows easy access for maintenance. A Universal Click-Fit coupling for 3/4", 1" and 1 1/4" inlet tubing is also included.