Is water leaching through plaster and gunite?

I doubt it is a plaster problem.

Is there a spa where that high wall is?

Gunite can wick water from the ground that comes out as efflorescence.


I don't know what I am looking at in pool3 with the colors and reflections on the water.

The back wall of the pool should have never been left unfinished. Gunite is not watertight. That wall should have been sealed using a cementitious water barrier and then either finished with tile, stone, or plaster. If it was finished with plaster it could be sealed with a consolidating primer layer and then painted. Leaving the bare concrete wall was and is a recipe for deterioration.

As @ajw22 said, the picture regarding the pool interior is unclear.