Bacteria House Bakki Rods The Bacteria House Bakki Rods are made of ceramic that has been heat treated at 1300 degrees for 60hrs. This tremendous amount of heat causes the ceramic to break its internal bonds thereby creating an extremely porous structure that has a much greater surface to allow very large bacteria populations to colonise. Due to the large quantities of tiny holes, mechanical filtration is also achieved. Large organic solids and decaying matter are degraded at a far greater speed than conventional media, and maintain the optimum ecological balance of aquarium. /p> <Each Bacteria House Bakki rod will hold enough bacteria to stabilise 200L of aquarium water Bacteria house is not made of calcium and as such will not erode and thus does not need maintaining, the bacteria house contains minerals and trace elements which is beneficial to aquarium life. Features: Porous biological filter media Great for sumps and wet/dry filters Large surface area perfect for colonising nitrifying bacteria. Suitable for freshwater aquariums, ponds and marine aquariums Size – Each Round BAKKI Rod measures 4cm x 17cmm Each Bakki rod will hold enough bacteria to stabilise 200L of aquarium water .