Yes, it powers the moving bed biological filter and is also vital to the cleaning process. You need an Evolution Aqua Air Pump 75 for a Nexus 220 and an Air Pump 95 for a Nexus 320. If you increase the amount of media in the outer chamber you may well need a more powerful airpump.
The correct size airpump to enable the filter media to move is detailed in the below:
- 50 - 75 litres = Use an Air Pump 75
- 75 - 100 litres = Use an Air Pump 95
- 100 - 150 litres = Use an Air Pump 130
- 150 - 300 litres = Use an Air Pump 150