Folks, I recently installed a basement toilet on stub-ups that were provide by the builder years earlier. The stub up I choose to use for the toilet is a 4" PVC pipe with an apparant trap in the line about 3-4' below the floor level. When I installed the closet flange and flushed, I had a slow flush which leads me to believe that I have a vent problem. Question 1: Can I simply add a mechanical studor vent to the toilet line? Question 2: Is there any problem with flushing down into a sewer line with a trap in it? and will the mechanical vent work?