K1 Media 50LEvolution Aqua Kalnes K1 is a high performance filter media designed for use in pond filtration systems. HOW IT WORKS: Maturing the K1 bio media is important because a delicate eco system is naturally developing for the bacteria involved in the nitrification process. K1 Media provides the maximum active surface area for the bacteria to colonise, more than other types of static media. It is this process which removes harmful ammonia and nitrite from