Imagine yourself in the water with your eyeballs just below the bottom of the red coping so that you can see where the vertical pool wall meets the under surface of the horizontal red coping. The “the vertical pool wall” is actually the top of the blue & white tile on the top of the pool wall.
As you know the tiles are held in place with the grout or whatever the proper term is & ideally there's no crack visible but I definitely have a small crack & I believe it is the cause of some “coping shifting” when water gets through that crack. While it is true that water should never rise that high it does sometimes before I can lower it and why have a crack there anyways.
I do realize that the caulk between the red coping and concrete deck would be more of a concern and I have dealt with that, so my question relates to the crack mentioned in my first sentence.
The pool is in need of replastering soon but I am going to delay that as long as I can get away with it so maybe two or three more years. I remember the last time they did the replaster that the tiles on the wall, at the water level, were left in place.
You guys don't have a problem with me placing a small bead of silicone caulk to seal that crack that I mentioned in the first sentence.it is not a large crack, more like a hairline not something like 1/8th of an inch. The silicone caulk adheres to concrete and is great stuff & I know that it is not designed to be "underwater" but it will definitely not be underwater very long if ever again. I'm thinking that grout is going to be a mess.