Need help with zoas in my biocube

Hey everybody, new to the forums so I hope to learn alot. I have a quick question and it seems to be stumping my local stores and my friend who is a marine biologist. Long story short I have had my zoas for 3 weeks now the first week they were wide open these past few days they are closed except 2 or 3 per colony. Myself and my friend did notice that the zoas are spreading pretty rapidly I might add, it kind of looks like long purple veins running all over my rock. I haven't seen any shrinking of the zoas or ones disappearing and I am not dosing anything. I will have to ask my friend my exact levels but he tested all my parameters and he said everything is where it needs to be. I have not added or changed anything in the tank since they've been introduced. I appreciate any help or insight I can get. Thank you