Leak with cold water only?

[no_salt_no_pool]

This spring, I noted a loss of 1"/24h within the first couple of weeks of opening (opened first weekend in May). This is with the pool completely covered with a solar blanket. I measured this loss rate with the pump running, and with the pump off, and also with the skimmer and returns plugged (there is no main drain, but I do have a light and steps). I take from this that the leak is happening somewhere within the pool walls. I did a close inspection of the liner and noted nothing. I did observe tiny bubbles coming from only one of the 2 returns when the pump is running.

The really bizarre thing is and this is my question, once the pool temperature approached & surpassed 80F, I have yet to observe a loss of water after 6 days! I'm wracking my brain trying to figure out how this is possible. My best theory is that the warmer water is causing whatever part is leaking to expand, and close off a crack or fissure, or maybe apply more pressure to a gasket?? Now I can't really have a diver come and search for the leak because it just isn't happening all of a sudden after 3 weeks of leaking.

Would really appreciate the forum's thoughts/opinions/ideas on why the leak would go away with warmer water.

 

[Pool Tool]

The only thing I can think of is a leak that has reached pressure equilibrium on both sides of the pool shell. Have you had a lot of rain lately, high or low water table? Maybe the surrounding soil was dry over the winter and now spring rains and the leak have helped to hide or even placate the leak. Truly that is a guess and probably a bad one

 

[no_salt_no_pool]

Thanks for the quick reply, Pool Tool, and the guess too . It's been a really dry spring. We've barely had any rain since March here.