I have seen Maximal Filter System Mini Max 1 for small tanks up to 40l in the internet. Do someone use this system? The system needs an air pump and works aerobious and anaerobious. So it produces CO2 and N2…?
it looks like a simple air driven sponge filter. should be OK for small tanks.
anaerobic filtration is of minor importance for freshwater aquariums. the amount of N2 that can be produced in a small filter is probably not significant.