I have a whisperflo 1 1/2 HP pump that used to pump like a charm. The outlet pressure is very low. The pressure gage reads 0 and I confirmed this by opening the valve on the top of the filter housing, and water just trickled out. I have cleaned all of the skimmers and the strainer, and checked the impeller for obstruction. I tried pulling from the drain and from the skimmers and no change. I think that the O-ring on the strainer basket is ok, but can't be sure. There are some small bubbles coming out of the jets, but not that many. The gage used to read somewhere around 5 psi but now is down to 0.
I really think this is a pump performance or inlet restriction problem, but I don't know what to do next. I'm getting algae now so I need to do something. Please help.