Hello, new member here. I have what may be a problem in my pool and I could use some help in understanding it. I bought a house 5 years ago with an IG gunite pool and I have done my best to maintain it and keep the water chemistry in balance. With the plaster starting to get rough and a few small spots of plaster starting to flake I decide to get the pool replastered. When the plaster was removed I discovered some "rust like" blotches on the surface of the gunite. I chipped away a small section of the gunite but could not find any rebar. When I could find some rebar it was nearly a foot away from the spot and buried in gunite with no sign of rust. There are several of these spots on the surface of the gunite in my pool. If these are rust stains I do not know what cause them. Any ideas? I have attached a picture of one example, before I started chipping away at it.