Pool Leak..... I'm losing my mind

[sgoosman]

I have a 40' x 20' inground vinyl lined pool. Shortly after closing last season, I noticed the pool water level dropping underneath my mesh safety cover after inspection the pool would lose water down to about 4-5 inches below the skimmer basket and then stop (oddly almost perfect winterization water level). I added water after the leak was noticed and within 2 weeks the water level was once again below the returns by 4-5 inches (photo of water level below, first year in 5 years that I had algae when opening).

So logical conclusion, I have a leak to find this spring.

Water level is below the skimmer and water returns so the leak has to be in the pool or the main drain line back to the pump. This winter I purchased an inspection scope and hydrophone. I opened the pool, used the 16 foot inspection scope on the main drain line from the pump and observed nothing. I then filled the pool and used the hydrophone to listen for leaks. I heard no leaks and then performed a bucket test, after 72 hrs the water level is identical to the start of the test with no rain.

Now I'm left scratching my head. Clearly, I had a leak where I was loosing upwards of 1/2 inch a day in the winter. Now in the spring there is no leak. I'm at a loss, I've never seen anything quite like this, rarely ever seen a self-sealing leak and certainly not in a pool.

I was wondering if anyone has a theory to explain this or have seen the phenomena. I'm fortunately the leak seems to have stopped but I don't trust it and I have no idea why it'd stop. Only theory right now is it's a expansion-related or water pressure is closing the leak or most likely my pool is trying to drive me insane.


Some additional pool information:

• 2 lights
• 2 aqua genie returns and skimmers (pool was here when I moved, if you don't like these know it was not my choice)
• Fiberglass stairs with vinyl liner fixed to the stairs
• main drain line with 2 connected returns in the pool
• All underground piping is 1.5 inch flex PVC
• Water level is below pool pump, pump removed for winter and pipes isolated with valves for the winter
• Deepend of pool has a dry well underneath (don't think it's relevant but who knows
• Location: Northern NJ, cold and normally I need to pump water out of the pool all winter
• Mesh safety Cover for winter

Any thoughts on or experience with a similar issue would be greatly appreciated.

Regards,

Scott

 

[mas985]

The leak is at the same level as where the water stopped.

I have a 40' x 20' inground vinyl lined pool. Shortly after closing last season, I noticed the pool water level dropping underneath my mesh safety cover after inspection the pool would lose water down to about 4-5 inches below the skimmer basket and then stop (oddly almost perfect winterization water level).

Then the leak is exactly at the level where the water stopped draining.

Is it at the same level as the pipe that attaches to the bottom of the skimmer?

Or are there any other wall fittings that are at the exact same level?

 

[Newdude]

Or are there any other wall fittings that are at the exact same level?

That's what I'm thinking. I've never been to sgoos house, but that's the level of his returns.

 

[sgoosman]

That was my thinking exactly. So I felt the vinyl linking around the entire pool. The only penetration on the pool at this level is the connection to the stairs. Both the returns and the skimmers are above water. Other possibilities are a crack in the light conduit or in the main drain.

I used the hydrophone to listen for potential leaks but no sound anywhere.

Further, now the leak has stopped which I have no explanation.

 

[sgoosman]

Wish that was correct. As stated in the original post, the previous owner built the pool with Aqua genie skimmers. the return is built into the skimmer.



The water level is 4-5 inches below the returns.