I saw season 9 opener where an AAV (air admittance valve) was used. I am wondering if that will solve my problem with my bathroom sink. The problem we are having is the sink is an under mount with no overflow / built in air channel. It just has the drain. Therefore when we use the sink it always backs up given an air bubble forms in the drain just under the plug. I was hoping adding an AAV will solve this problem by letting air into the pipe. I am not very familiar with plumbing so any help you can provide me will be greatly appreciated. Thank You.