Planted Tank Guru
Join Date: Nov 2009
Location: Missouri united states
If it is a large tank ,I would run both filter's.
If not,,I would run one, and when it became dirty,,swap it out for clean one.
If your gonna want the flow from two filter's,,you may as well fill em with mechanical media and get the benefit's of more particulates being caught.
If tank is home for large waste producing fish san's plant's,,then fill one with bio-media and the other with mechanical media.