I built an addition now Im moving ny laundry area so I need to run new drain. In the process I also needed to install a sump pump under the addition,I tied the new drain into an existing 1 1/2 galviized from there I have a 9ft run 1 1/2 pvc to a 45deg T the sump is tied in at this point then another 13ft run to a 90deg left then 2ft to a 90deg up with a 3ft standing drain for washing machine. problem is when sump runs the water tries to back up thru standing drain pipe, when sump shuts off it drains back down and you can hear it gurgeling. Do I need to put in a vent stack on this drain and if so where should I put it in my run.