Zoas Closed Up

Over the past few days some of my zoas have been closing up. The odd thing about it is, they are closing up in groups depending on color morph. It started with my green zoas and now my tubbs blue zoas. I don't see any parasites on them. I won't have test results until tomorrow afternoon. My salt mix is giving the new water a yellowish tint. Any ideas? ​

 

How long has it been? I have a few colonies that will close up for a day or two from time to time. Supposedly some do this to clean themselves every so often. Unless it's been 4-5 days, I wouldn't get too worried just yet, if you have nothing to suspect.

 

The tubbs blue started today and the radioactive dragon eyes have been closed for a week.

 

Disregard where this is hosted (8)), but this is a great resource:
25 Reasons why your polyps won't expand. - Reef Central Online Community

 

my bright greens zoas did something similar ahile back, they just closed up for over a week or so and then one day they were back to normal. I couldnt tell you what happened, but after they did it seemed that they started to split like crazy.