I hope someone can help me with what I consider a weird problem. Inground pool, 1 1/2 hp pump, sand filter. I just returned to my vacation home and needed to vacuum the pool. (vacuum through the skimmer opening) In the past I have had good suction. Now I have very little suction. I have no separate inline valves controlling the bottom drain and skimmer...both connect to each other under ground and a single line runs to the pump input. So the only way I have to draw suction only from the skimmer is to cover the bottom drain. I tried covering it with a upended five gallon bucket and that seems to work fairly well. (the bucket is sucked down to the bottom). But the suction does not increase at the skimmer. In addition, I see no decrease in the outflow. How can it be that I can effectively cover both bottom drain and skimmer openings and still have outflow? I can't make sense out of it... seems like it has to drawing water from somewhere else in the pool. But where?