I am not seeing a bulkhead except for a cutoff portion of the pic in the top left corner.
Rest looks to be PVC tubing to a coupling fitting to a barb fitting to soft braided tubing.
Not sure what the piece is on top of the soft tubing (right tube).
The pipe on the left seems to be the return possibly? Going back into the tank with a similar tubing usage except for top of the soft tubing goes into a 90 degree elbow then into the bulkhead.