I moved into a house with a 10K gallon pool about 1.5 yrs ago. I'm still learning how to maintain a pool and this site has been a huge help. Pool came with a Pentair Challenger pump (1.5 hp) that has been working okay since we inherited it. Had some issues with air in the intake--nothing major, but enough to spur an overhaul with new o-rings. Pump worked fine for ~2 mo after that. Started getting noisy about two weeks ago, got progressively noisier, and woke up last week to find that the pump was running without water flowing through it. Wouldn't prime. I suspected the pump was toast and bought a 2-speed Pentair Superflo. Installed it today and found that it seems to be running (motor-wise) fine, but not priming. I'm now suspecting that the old pump was fine, and that I have a big leak in my underground intake plumbing. Any thoughts would be greatly appreciated!