Pressure filter sponges

The heart of a filter is its filter sponges: Filter sponges not only complete classic filtration, but also offer the smallest bacteria a lot of living space. This biological oasis in the filter sponges ensures that the toxins produced in the pond are converted: In the blue sponges toxic substances are converted into harmless algae stimulating substances (nitrification), which in turn are converted into naturally occurring gases in the black sponges (denitrification).