The Inland Seas Nu-Clear Model 547 is perfect for applications where a biological filter outside the tank or pond is desired, or when existing biological filtration is not sufficient. The filter contains three gallons of premium 1? Bio Balls with a combined surface area of over 60 sq. ft. on a high flow grid. This is enough biological filtration for systems up to 180 gallons. Although this filter resists trapping, we suggest using it after a Model 522 or Model 533 mechanical filter. Other Features:Heavy duty molded PVC construction with a stainless steel lid clamp for secure leak free operation2 year manufacturer guaranteeFilter bodies are approximately 13" wide and 12.5" tall (overall width with fittings is 15?). An additional clearance of 8? above the filter is required to remove the cartridge for cleaningCan be used with the Model 1547 Extension Kit to double the filtering capacity1" FNPT inlet and outlet ports allowing for higher flow rates (up to 1,200 gallons/hr) than similar filters with 3/4? ports.All models come with adapters for 3/4" and 1" hose, stainless steel hose clamps, Teflon tape, and a drain valveDoes not include pump, hose or a method for connecting the filter to your tank. We highly recommend using the Inland Sea Suctions and Returns with the Nu-Clear Filters, and we carry several models of aquarium and pond water pumps.