We've had some nasty wind, so I've been out cleaning MAJOR debris from our 30K gallon pool. We have a Pentair DE filter that my husband cleaned out this afternoon. It was working just fine, then out of the blue the pressure dropped to 0 psi. I cleaned out the basket which was very full after only 10 min of sweeping and got back to work. After sweeping for another 5 min or so, the pressure dropped to 0 again. I cleaned out the basket again, it was slightly less full this time. Now, the filter won't prime. I ran it for 10min waiting, but 0 psi. Any suggestions?