I have a pool with plumbing 3 ft down with concrete covering the pipe. Now still cannot find the leak tried everything Except gas . What advise can you give . Thanks

are you using air to pressurize line? I find no difference between air and gas (nitrogen) in terms of lstening for leak. We sometimes use Helium with a Helium sniffer but 95% of time we find leak with XLT30 or XLT 17.
Rob

Air and water together at a fairly high pressure should be able to be heard but that repair will be a bit tough. It may be easier (depending on the configuration) for you to cut the deck back to the filter and replace the line.

Working three feet down plus having to break concrete at that level will be absolutely no fun, but should be plenty profitable!!!