My pool is a 14 year old 13,000 gal in-ground fiberglass with a 2HP Pentair pump. Two drains are near bottom, and a single skimmer. All piping is below ground, and both drain and skimmer return lines join at a Jandy valve just prior to the pump basket.
Last week when connecting a vacuum broom into the skimmer, I lost suction and pump became air bound. Pulled out vacuum hose and restated pump, which operated normally. I examined the vacuum hose for leaks and found none . Tried repeating vacuum while holding the whole length of hose below water and after about 20-30 seconds, pump lost suction and became air bound. (Tried using both ends of vacuum hose also, with same result.)
System seems to run just fine until I push the vacuum hose into the return line opening at the bottom of the skimmer. I noticed a noise after about 30 seconds that sounds like it might be air being pulled in, but I can't see any bubbles or evidence--just the pump losing suction.
Any thoughts as to further troubleshooting or repair? I've examined all of the other usual suspects... thanks!