I have backwashed my system many times to get it to start flowing, but as soon as I fully open my ball valve on my return line the flow drops to a trickle. I can leave it partially closed and the flow is ok..not perfect. I have an intex 2650 sand pump/filter hard pipped with 1 1/2' pvc. I replaced the plunger valves with ball valves. I have noticed a small drip right at the output of the return line. Is there a way of testing for air leaks? When I do get the flow going good and I turn off the pump to switch it to the timer the water in the skimmer goes way down to where I need to open the lid to let the air out again. I am just at wits end on this and I am driving my wife nuts..