Zoas do fine one day and then bad the next

[radioman22]

I have had these green Eagle eye? zoas for a year now and all of a sudden they are closing up starting in the front. Has anyone seen this happen before or know what it could be? I also have another colony that isn't opening fully but was looking good just days ago.. You can see how they looked a few days ago from the first picture. At the same time my rastas are doing great along with some other small colonies.
Salinity 1.025
Alk 10
Calcium 480ppm
Tank Size 5g
20% water change once a week

 

[DSC reef]

Million dollar question right there. In the years I've kept zoas there's always some that seem to up and melt while others thrive. Rastas were the only bullet proof zoas we've kept. Check for pests like aptasia, I've had babies sprout up causing issues.

 

[radioman22]

Thanks for the input. I was looking for aptasia but didn't see any. I've had colonies close up and then open back up. Maybe it is just this colonies turn to be moody.