bought a home with a in ground pool, I noticed a vacuum line port in the pool wall so I removed the screw plug but there is no suction. I only have 1 jandy valve and I have set it off in both directions and there is no difference in the suction at the skimmer. Could this vacuum port not be plumbed? I stuck a garden hose in there and it goes back about 5 feet then stops, I don't know if its a bend or what but still no suction. I currently vacuum the pool through the skimmer but would like to put a vacuum in the pool and not obstruct the skimmer basket.