I am going away on vacant. Normally I would get the pool up to shock level figure out when I need to add chlorine based on my average consumption and pre measure chlorine so someone can just stop by dump a bottle in and go. This year they are away as well. But will be back before me. The math works out that if I bring my pool up to mustard shock level I they will be back in enough time to add the chlorine to the pool in enough time. But I swear I read somewhere on the site that getting the levels that high can be very dangerous and should only be used as a last resort. Am I safe if I only bring the level up that high once?