I shocked the pool and ran to the store for more test strips. When I got home my 17 year old and her friend were in the pool. The chlorine level was at the top of the test. I made them get out and shower. Is this something that I should be concerned about (other than my own stupidity for not leaving a note) healthwise? I didn't think it warranted a call to poison control. How long will it take for the level of the chlorine to come down? I added more water and am leaving the cover off over night.