When I opened the pool, there was no pressure. I though there maybe a clog in the line, so I put a hose down the swimmer. The filter ran fine all day while I was cleaning, and vacuuming. The next morning, again no pressure and the hose trick worked. I have check everything I can think of. But yesterday I had left my backwash hose attacked to the multi port value, and the hose has a significant amount of water in it. There is a lot of air in the system every morning. Could the multi port value be bad?