Eheim SUBSTRATpro+O2xygen is the latest evolution of Eheims trusted biological filter media - now enhanced with integrated O2xygen for improved oxygen supply in the filtration circuit. The highly porous sintered glass spheres offer a vast surface area for beneficial bacteria, ensuring long-lasting and highly effective biological water purification.The Eheim SUBSTRATpro+O2xygen - a filter medium that revolutionises biological water treatment. This latest development, based on the tried and tested SUBSTRATpro, combines first-class materials with stateof-the-art technology. The secret behind the extraordinary effect of Eheim SUBSTRATpro+O2xygen lies in the gemstone mineral tourmaline it contains. Thanks to its unique pyroelectric properties, it generates electron-activated oxygen (super oxygen O2-) on contact with water, which optimises the oxygen supply in the filter substrate and creates ideal conditions for filter bacteria. This stimulates the metabolic processes in the aquarium and a