With your cya 5 is your minimum chlorine level. I would suggest you take it back to shock and keep there for a couple of days. When you hold the chlorine overnight, you can start to let it drift back down, but keep it at the high side of your chlorine level which will be 10ppms for a couple of weeks. This way any algae that is just starting will get killed off - if the chlorine levels are too low, it is easy for it to get a foothold again Give a good dose of high chlorine and get rid of it once and for all