The ultimate leak checking bubbles there is..
Take a spray bottle with the "stream" function and put Dawn dish washing soap to about 1/3 of the bottle, then put another 1/3 of the bottle of glycerin, top it off with some soft water, spring water works in a pinch.
Put it in the refrigerator and use it cold, make sure it is shaken very well before you put it in the fridge.
I have had this stuff make 2' in diameter bubbles....

If it were mine, I would shoot a little R22 refrigerant in it and leak check it with an ultrasonic leak detector.... Found an air mattress leak in about 30 seconds.
