I think I know the answer, but I’m going to ask anyway.
I’ve been winterizing my own pools for decades. I’m entering my 6th season with this particular inground pool. This past winter was one of the coldest on record here in NJ. I opened my pool yesterday and have bubbles out the returns, so it’s getting air from somewhere.
I have floor drains and one simmer. Each has a valve. So I was easily able to isolate the air leak to the skimmer suction line. When I close the skimmer valve and leave the floor drains open, the bubbles eventually clear up. Open the skimmer valve, bubbles reappear.
The leak isn’t big enough for the pump to lose its prime - it starts up in the morning just fine. I don’t hear the gravelly cavitation noises in the system, and I have strong return output. But there’s still lots of bubbles out of the returns indicating a leak.
I replaced the multivalve gaskets just before I opened the pool, but I’ve ruled that out by isolating the floor drain and skimmer suction lines one at a time. If it were the valve, the problem wouldn’t clear up when I shut off the skimmer line.
The only union between the skimmer and the pump is just before the valve. I disassembled it, lubed it, and put it back together. Didn’t help. I checked all of the suction side fittings with soapy bubbles and didn’t find a leak. So unfortunately it has to be underground. I’m not losing any water with the pump shut off, so it has to be a small leak.
I don’t see how it could have frozen. When I removed the gizmo, I got the rush of bubbles and air so it was still sealed. I had also dumped about a gallon of antifreeze into the line after I evacuated it and before installing the gizmo. But here we are…
I can make a pressure test rig, and will do that, but I’m pretty sure it’s going to tell me what I already know. The question now is how to pinpoint the leak? It’s about a 40-foot run from the skimmer to the pump. Will air pressure eventually make the leak known somehow? Or should I hook up a hose to the line and see if/where water starts to come up from the ground. Complicating factor is the patio around the pool, but the good thing is that it’s paver blocks and not concrete (easy-ish to remove/replace).
Any and all advice would be greatly appreciated.