I'm trying to locate ≈ 300 gallon per day leak in a 2ft. elevated pool side gunite spa
I'm unsure of some of my test results ;

what I do know;
tunnel / cave under pool shed reviled nothing
client that doesn't want their slate over concrete & rebar deck violated / diamond saw & jack hammer
air pump & line has been abandoned.
it's not the suction side.
with all 4 extended jet nozzels plugged , spa does't leak down to pool level
regardless of how far I insert inflatable plug into supply line [ within a couple of feet from spa ] leak still occurs.
confusion / uncertainty starts here;
when plugging 2" supply line and pumping air into one of the otherwise plugged nozzels gurgling and water show at the net jet in line?
seems to me with nozzels plugged there shouldn’t be a link to the air side ?

would / do > liquid leak stop products work or be applicable in this situation ?