I replaced the 90 degree elbow to the 3" waste drain pipe, and put down a new subfloor. The elbow is now even with the top of my 3/4" plywood floor. The toilet flange has about 1/2" clearance from the top of the plywood floor. Is this acceptable? Or do I need to cut down the top of the ABS plastic elbow or add another layer of 1/4" plywood on the subfloor?