Fluval U3 Media Value PackFluval U3 Media Value Pack Specifically designed for use with the U Series internal filters, featuring all the quality, effectiveness and convenience you've come to expect from the leader in aquatic filtration. These value packs deliver all the necessary media required to keep your filter operating at peak performance for up to 6 months. Biomax Complex pore system maximises water contact time and surface area to support and promote beneficial bacteria