pool leak

[Eric Smethurst]

When usimg the skimmer I noticed air bubbles coming from one of the three impulors accompanied with a loss of water maybe 1" over 24 hours. Also there is air in the pump sight glass area but if I then open the drain line 3/4 then the air bubbles disappear both in the sight glass and the impulsor. It appears to me that opening the drain line takes the pressure off the skimmer line
I have tested the water loss thoroughly and have found that if I plug the suspected impulsor then the pool will drain down just below the lowest level of the skimmer boxes. No more water will be lost until I unplug the impulsor. The water level will then drop just below the aperture and there will be no further water loss. Am I correct in assuming that the skimmer box is is where the leak is and is also drawing air.
I know that water will find its own level and this can be confusing as far as locating precisely which end of a skimmer line is leaking.
I would be pleased to receive any opinions relating to this.