Ok. So, even though a chlorine reading of 10ppm is a little high for a pool with CYA less than 30ppm, (unless you are shocking the pool), it will come down on its own. Low CYA pools don't hang on to chlorine very long on hot sunny days.

Nothing to worry about. If you swim today while the chlorine is at 10ppm, just wear an old swimsuit. It won't hurt you at all.