Since you still have combined chlorine, I would take the level up to 15 to shock. It sounds like you just didn't get it high enough to finish the job. You can put a skimmer sock on the filter, or use an old pair of tights or pantyhose, cut off the leg and put the foot in the skimmer, wrapping the leg around the top of the basket. Keep the filter running 24/7. Keep the chlorine at 15 until it holds overnight, and you have no combined chlorine.