If anyone added that shock-n-swim, it's going to mess with the chlorine test for a while.
Compare your current readings with [FC/CYA][/FC/CYA] and if you're above minimum but below shock level, it's okay to swim. And if someone added that shock n swim, who knows? You could have a bunch of chlorine, it could all be MPS. People swim in rivers and lakes all the time and live to tell about it.
Hi, I asked and my dad said he definitely only did the pH down product. I'll check the chart!