This unit is ideal as a primary filter for aquariums from 10-55 gallons and can be used as a supplemental filter on larger aquariums. The protein skimmer will operate effectively on aquariums up to 125 gallons. The Skilter 250 has an effective flow rate of up to 250 gallons per hour. It is packaged complete and ready-to-go including a Bio-Matrix dual-media filter cartridge. Made in the USA. SKILTER