Could it be the skimmer?

[MizTanks]

Ever since I placed my skimmer back in my tank, all the zoas near it are dying off. I mean all of them!!
On the right hand side you can see where the skimmer is. See where all the zoas are receding? It's terrible!


Here's how they look now



Here's what they used to look like about 3-4 months ago.