Just did a job where a competitor isolated the Polaris Line as the leak source. He reported that he was unable to hear any noise with his XLT17 but the line would not old any pressure. He was right. The line wouldn't hold pressure, but I heard nothing with my XLT30. It was a fairly short run of black poly pipe, so I ended up replumbing the line. Also my Helium detector has proven useless during hot humid summers down here in the south. (Gow Mac confirmed this issue with humidity). Can anyone explain why this leak made no sound. My only guess is that a large void space washed out around the leak and the air was not penetrating the moist soil therefore no noise was created. Don't know if that makes sense or not. The old pipe was not excavated since I used a different route for replumb.

Suggestions:
Run the PT with water, it will saturate the ground, sometimes you will hear water when you cannot hear air, water will fill any void space that may be preventing you from hearing the air, after running water switch back to air, often you can now hear the air sound with the soil and any voids filled with water, and also don't forget to try the hydrophone, with the pipe valved off at the pump, insert the hydrophone at the pool (it will pick up the whooshing sound of the water movement along the way and when you get close the whooshing will increase and also have dripping sounds, and when you go past the leak, you will have a sudden drop in the sounds
Hope this helps
Bruce
poolrepairdiver.com

The replumb was the right way to go. Poly pipe repair with at least 60psi from polaris pump is a recipe for a call back anyway

Thanks for the advise. I tried the PT with water with no luck, but the hydrophone sounds promising. I do not own one but I'm going to purchase one now. I was happy with the replumb, but it still bothered me that I never found the leak. I'm always looking to improve. It sounds like I need some equipment upgrades.