Evolution Aqua K1 Micro Media 50 LitreK1 media has been used by Evolution Aqua in Koi filtration systems for a number of years. This new type of filter media, K1 Micro, contains all of the benefits of traditional K1 media but is extruded in a much smaller form. The small wheel shaped filter media pieces provide a significantly increased protected surface area per cubic metre when compared to standard K1 for bacteria to colonise. This makes K1 Micro an ideal filter media for aquariums of