Mysterious air leak

[BApool]

Hello there, hoping you can help as I'm at my wit's end over this. Purchased a home with an in ground pool over the winter and I just opened it up for the first time. I have a hayward progrid DE filter with a 1hp superpump. 1 skimmer and a small inlet "hole" a few feet from the skimmer. 1 return and a line plumbed for the slide, which was removed. There is also a hayward salt generator that is not currently plugged in due to the water temperature.


I primed the pump, poured in the DE and things seemed fine. After about an hour I noticed some air in the pump basket, not a ton but a bit. I ran a garden hose over all the connections on the suction side and found air getting in where the basket connects to the PVC, pulled it off, wrapped it in Teflon tape and tightened it up, the air seemed to dissipate.

I let it run over night and in the morning the basket was half empty and there was minimal suction at the skimmer and minimal flow at the return. I then greased every o ring I could find, pulled apart the diverter valve, and actually replaced the basket o ring even though the existing one seemed to be in good shape.

A few things:
1) The pump never loses prime, but every time I start it up, opening the pressure valve on the filter releases a lot of air, even when there's no bubbles in the basket.

2)The basket looks good at startup and then slowly accumulates air.

3) If I put the multivalve on recirc, it seems to run better.

4) The air valve on the filter is constantly letting out a small amount of air, if you put your finger over the hole you can feel it. (Not sure if this is normal)

5) the pressure on the filter goes to 20 at startup and stays there for a long while, even though the pool is not clear and it's run for about 15 total hours without a backwash. The only time I see it over 20 is when the basket is half water, half air and even then it only gets to 28 or so.

6) when I turn the pump off I hear a gurgling sound on the return side, I can't isolate where exactly but it seems to be the returns.

7) theres a steady stream of small bubbles coming out of the return, regardless of the amount of air in the pump basket, in filter it seems like there are spurts of water and air, recirc is more steady water with the small bubbles.

8) moving the diverter between the skimmer and inlet hole does not seem to change anything so I sort of doubt the issue is between the pool and diverter, but who knows.

I feel like I've eliminated everything I can. Plenty of water, skimmer is free of debris. O-rings are lubed and good, all threaded connections and drain plugs are taped and tight, the pump basket and lid are solid. What's left?

 

[BApool]

One new data point, I let it run overnight on recirculate and the pump basket looked fine this morning, so the issue only really exists when water flows through the filter.

 

[richardc]

I am no expert but can only provide you with my experience. I have a large in ground with two skimmers, and a main drain. I have always had air leaks, and could never find the source of the leak(s). My pump basket would show air bubbles, and the extent of the air would vary from day to day. I tried every trick in the book to find the source all to no avail. I assumed that the leak was below ground in one or more of my pipes. Here is what happened. My pump impeller became clogged with debris on startup this year. (it had never happened previously to my knowledge). Not being mechanically inclined, I didn't realize that the pump is enclosed in a removable case that unscrews from the far right side (rear) of the pump. This area is at the far end of the pump, and way beyond the the discharge pressurized water supply side tube that heads to the filter. So, the end cap was loosened and the pump body slid out so that the impeller was exposed. At that point it was clear that the impeller was clogged with debris. The debris was removed manually, and the pump body reinserted in the case, and fully tightened down. No more air leaks!! Mind you this is after 20 years of leaking, and no one ever suggested, or examined the rear end of the case for leaking, or even suggested that the impeller be cleaned ! Given that my leak was seemingly passed the point where pressurized water was discharged, I never would have thought to investigate that part of the pump. Indeed, I had no idea the pump disassembled in that area, and could be the source of a leak.

The literature suggests that the service pad be thoroughly searched for leaks, and in my case it turned out to be true, but in an unlikely place. However, in thinking about it, I suppose it's not surprising that the pump was the main culprit. Good luck, and maybe this will help!