Zoa stopped opening

[KPH]

Hello all!
Ive had these dragon eye Zoas for about 6 or 7 weeks now. They’ve been doing brilliantly. Always open. Always vibrant. And it’s gown by about double. I’ve slowly added two different Zoas on the same rock over the last month. The last one I added was about two or so weeks ago and it’s the one at the bottom of the picture. It never really opened up super well so I moved the whole rock away from the glass and rotated it a little bit thinking it was maybe a little crowded on the glass. Now it’s opening up more regularly but since Thursday (when I moved the rock) it hasn’t opened. Broadcast fed some reef roids early this morning and it opened up but has since returned to hiding. I’ve dosed iodine as well. Any ideas based on the picture. Just did a water change also. parameters below:

temp: 78
PH: 8.3
Ammonia: 0
Nitrite: 0
Nitrate: 10

Thoughts? Ideas?
Thanks!!

 

[vetteguy53081]

infrequent feeding and ultra low nutrient conditions can lead to entire colony meltdowns. The "cheesing out" syndrome can be the result of limited nutrients (Phosphates, Nitrates). Zoanthids need fish poop, dissolved food matter and the resulting nutrients to thrive.
generally, zoanthids can thrive in the same conditions that SPS corals do. Good dissolved organics levels, high light, good nutrient export, low nutrient byproducts like Nitrates and Phosphates. I am not claiming that Zoanthids need the pristine conditions that SPS corals require but they do thrive in similar conditions. However, I have learned from experience that Phosphate levels below .02 can be detrimental to the health of the polyps. Always remember that Nitrogen and Phosphorus are the building blocks for coral life, so zero Nitrate reading or zero Phosphate reading are not a good thing for your aquarium life.
Zoanthids do not require the level of, or the amount of trace elements that SPS corals do but they certainly benefit from consistent water quality/chemistry. Qualities that should be monitored regularly in a reef aquarium are -- Alkalinity, Calcium, Magnesium, Iodine, temperature, Phosphates, Nitrates, and pH. I am not indicating that they require all of the aforementioned items specifically, only that consistent levels keep Zoanthids happy and healthy. My chemistry is consistently maintained in this range:

dKH: 8.0 - 9.0
Calcium: 430 - 440
Magnesium: 1250 - 1300
Iodine: Maintained via regular water changes (be careful if you are dosing without testing!)
Temperature: 77 - 79 degrees
pH: 8.1-8.2
Phosphates: .02 - .03
Nitrates < 5

Adding iodide weekly also benefits them

 

[KPH]

I also changed my light schedule. It was starting up at 6am and finally shutting off for the night at 7pm, with three hours of that total being sunrise and sunset and the accompanying ramp up/ramp down. Since Thursday of last week, it’s been running 10am start to 8pm lights out. Still with the same three hours with the sunrise and sunset with ramp up /ramp down. Would that have had a significant impact on this one single Zoa? Every other coral I have didn’t miss a beat.