So my friend recently purchased a home. The previous homeowner did not leave any chemicals. The pool was crystal clear but I tested it and it was low on FC. I shocked with 48oz of cal-hypo through the skimmer and it instantly shot out a green cloud from the return that to this day still lingers as a green tint to the water. I assumed either copper or bromine for the green cloud. The chlorine seems to hold fairly well so I am leaning more towards copper. I used a new copper test kit and it came up with no indication of copper. Thinking that the test might have bleached out I ran the test again with a dilution of 1:1 and again with a dilution of 1:3 with the same result of 0 copper presence. Also maybe the results show 0 because the copper came out of solution during the shocking?
Here are some pictures
The image with the girl and the dog is the before shocking picture the other 2 are the after pictures