5 Compartments In My Filter Tray

[CFC]

you just love to go against the experience of everyone else dont you ColinT.

Modern hi tech biological media's like bio balls or sphintered glass and ceramic media's like Eheims Efisubstrat Pro or Alfagrog have far larger surface area per litre of volume for bacteria to colonise than sponges and are designed to allow the flow of oxygenated water past the media to be greater so ammonia can be processed faster.
Sponges will do the job no doubt, but they are prone to clogging and unless cleaned regularly tunneling can occur which makes the filter more maintenance intensive. Sponges do have their place though as they provide great mechanical filtration for preventing medium sized particals from reaching the fine floss media at the end of the filtration process so the floss lasts longer and needs replacing less frequently.

The reason so many filters come supplied with just sponge media these days is purely economics, sponges are a cheap filler media that provide both mechanical and biological media with little expense.

 

[andywg]

I am not a fan of putting floss at the end. The more gunk that gets into the area the bio bacteria are, the quicker the bio media gets clogged up with gunk and stops working correctly. I would always have it go from coarse mechanical to fine, then bio and then out to the tank.

I find bioballs trap sediment all to well - causing maintenance to be more frequent. This is why I changed my sumps to wet/dry and installed exposed sponges and filter floss to catch the mechanical waste before it can get into the chamber holding the bio media. In this way I haven't had to touch the bioballs in over 2 years.