Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I would not do this. Each filter was designed to work without other pumps (or filters) in line with it.
I would run each filter separately through its own bulkhead, or one filter could return over the side and run the pump through the other bulkhead.
Try to aim all the water coming into the tank in one unified circulation pattern. Do not criss-cross the inlets.