I have had good success with my Emperor 400s by cutting 50 micron felt that I got from F&S to fit the second cartridge cages. It catches lots of stuff and I can easily wash it and return it to service. I get great physical filtration without a steady consumables cost.
However, I would like to try even finer material if I could find it so I could filter out smaller algae and polish the water even better. Does anyone know where to find finer material that works for this purpose?