Dunno about the pop-up . . . but you've got copper staining on your plaster. This is something to DEFINITELY keep in mind. High chlorine levels + high pH can cause that blue copper to turn black! Be SURE to tell people you've got widespread uniform blue-green copper staining when you post any chemical questions here.

You probably need to run standard chlorine & stabilizer levels + polyquat if you ever stop using the copper.