its a Aquaripure denitrator. this is what it says about it.
A denitrator is a biological filter that removes nitrate (NO3) from the aquarium. A denitrator filter uses anaerobic bacteria to break down nitrate into nitrogen gas (N2), which escapes into the atmosphere, the result is nitrate free effluent. A denitrator achieves this in an extremely safe and controlled environment. They have even been used to make water high in nitrates safe for human consumption.
Anyone heard of it before? or does anyone know anything about this system?