The Interpet PF Filtration system represents the most versatile, comprehensive and easy-to-use water filters available. Effective filtration provides the ideal conditions for your aquarium fish, plants and coral to thrive. With its unique, easily located cradle the filters are simple to fit. The PF range features a triple stage filtration system with mechanical, chemical and biological filtration. The PF4 provides effective aeration with rocker switch controlled powerful venturi. Its low maintenance design features an easy to clean cartridge. The patented aqua valve is a non-return valve that prevents waste from being dumped back into the aquarium when the filter is removed. The PF4 is fully adjustable, with easy flow rate and direction adjustment. The PF4 is ideal for aquariums up to 120cm (48”) in length and from 127-182 litres (28-40 gallons) in volume.