Filter material half life
All filter materials including plastic materials which are supposed to have a high microscopic surface area become polished after a while so in the end one type of filter media is just about as good as another for a given macroscopic surface area. This happens because the colonies of bacteria actually smoothen the surface of microscopically rough surfaces. I worked for years together with a french recirculation systems company who had their filter media in trickle towers analysed regularly. All Bioball types used for instance, lost microscopic roughness at the latest after 5 years. This means you should also partially change plastic medias every couple of years (not just stuff like efisubstrate) if you need high performance from your biofilter. I understand that different media types have widely differing surface areas and I am not trying to spark a debate about which is better but state the fact that ALL filter materials even ceramics, sand and scrubbiesreduce in surface area over time.