I have a 30 year old "black bottomed" gunite pool in Hawaii that uses about
150 gallons of water daily. [I carefully measured.] Its probably done this for years but this has only become noticable now that our daily rains have ceased.
I've done the normal: plugged all inlets, outlets, used dye looking for movement, checked the tile line. I've closed the man drain and packed some A+B Epoxy around that fitting in case that was a path. I've packed the cable fitting for the underwater light with epoxy also.
Still, the level drops the same whether the pump is on or off.
For want of any other cause, that leads me to suspect the "plaster."
It is not modern "smooth" black plaster but was probably cement mixed with Hawaiian lava sand. Relatively coarse grains are visible on close inspection buy not spalling or gouges. The material extends evenly to the tile line. The plaster is intact as far as I can tell.
There is a slighly brownish discoloration [doesn't bother me] at the deepest end of the pool. Perhaps a 10 foot circle. But even there, the plaster feels intact.
Would a gunite shell leak without "real" plaster? Is it likely that this plaster is simply allowing seepage?
Thank you for any comments.