K3 Bio Media has been one of the most well documented biological solutions for the treatment of water for ponds, aquariums, and waste water. K3 Bio Media measures 25 x 12 mm. The K3 Bio Media is perfect DIY applications for moving bed filter applications and is research proven to be efficient. The K3 Bio Media provides maximum surface area for the growth of beneficial bacteria to colonize making this media very efficient. With matured bacteria, this media is the most efficient in removing ammonia and nitrites. The K3 Bio Media is designed to be self-cleaning and to constantly move freely within your filter, requiring little to no maintenance.