You need to keep the shock level up until you're not losing any chlorine when measuring at sundown and sunup. After that you can let the chlorine start to drift back down, and the kids can get back in. Once it gets below 8 or 9 ppm I wouldn't have a problem getting back in, although I'd wear old suits in case of fading and rinse their hair well after getting out to make sure the chlorine doesn't dry it out.

Janet