Locating leak

[husky193]

To anyone that can help out. I am using the xlt30 h to locate a leak. I’ve added 10 psi of pressure to the line and it’s dripping pressure. 1 psi per min. So I am assuming this is a very small leak. I’ve used the hydrophone to scan the inside of the pool and normally I can hear it if it’s close. So this leak is further back. I’ve tried listening on the deck and no noises. There is grass behind the deck and I do have the probe for this too. Just not to familiar with it. I know what noise I need to listen out for and I tried to visualize the easy route for the plumbing to be. Just can’t locate the leak. Customer is losing 1/2” of water per day. I emptied the pipe from water to assure there is a loss in pressure and tried listening with no success. Tried with water and air and still nothing. I am using a normal compressor to introduce air.
I did however find leaks in the liner. They have been patched and re tested. Now resulting in no liner leakage.
I even tried changing the switch at the back of the unit from big foot to probe and nothing.
When using the grass probe should I leave the setting on Bigfoot??
Any help would be great.

[dynamictiger]

Hmmmm

I dont know this device. However here is what I would do.

1 psi per min sounds like air in the line.

Seal the lower end of the pipe. I use expanding plumbers plugs. Fit a cross to the top end of the pipe.

On the three sides of the cross install a valve. On one side attach a connection for the garden hose, on other side fit a pressure gauge and leave top as valve.

Open valve to gauuge, top and garden hose side. Fill the line untl have a steady flow of water from the top valve, so know all air cleared of pipe. Then close this valve.

Watch gauge and bring pressure to about 200 kPa or about 30 psi.

Close garden hose valve.

Pressure shouldn't drop. If see slow drop then likely air still trapped. Leave for about 12 hours.. Leak will drop pressure to 0, air trapped will usually drop pressure abut 1/2 to 1/4 starting. A small difference is to be expected with temperature differences but can be corrected if need.