Zoas closed

[welshgazz]

Hi, my small colony of zoas has partially closed today, I have made no alterations to light or flow. I checked parameters and noticed that phosphate was pretty much unreadable on my salifert test kit. All my other corals are doing fine, fully open candy cane, Duncan, toadstool and nephia coral. Previous levels of phosphate were 0.25. can this lead to zoa closure?

 

[cdemoss01]

@vetteguy53081 should be able to help with this!

 

[vetteguy53081]

Hi, my small colony of zoas has partially closed today, I have made no alterations to light or flow. I checked parameters and noticed that phosphate was pretty much unreadable on my salifert test kit. All my other corals are doing fine, fully open candy cane, Duncan, toadstool and nephia coral. Previous levels of phosphate were 0.25. can this lead to zoa closure?

Assure phos is not elevated, light not too bright and flow not excessive. I'll touch more in a bit as im tied up with a task

 

[Red_Beard]

Almost anything can cause that. I would not be overly concerned unless they stay closed for 2 days or so. A fish brushing them or a snail crawling on them or a change in flow or or or can cause them to close up for a bit. If those are at play, they will open back up soon enough. If it is chemistry or something more serious, they will not until the cause is addressed.

 

[vetteguy53081]

Assure phos is not elevated, light not too bright and flow not excessive. I'll touch more in a bit as im tied up with a task

To touch on my message, It can be to too much light or water flow, sudden change of parameters and even use of vodka or carbon dosing that reduces nitrate quickly. Assure specific gravity and Phos has not become elevated.
This is likely NOT a light issue although most zoa favor low light. If It is melting its a sign of stress. Oten a simple dip in Lugols iodine can perk them up. There are a number of factors why zoas close up especially water movement/flow as zoas do not require the consistent high flow conditions that SPS corals do. I would consider running moderate flow which is ideal but Zoa can adapt to low or high flow. In high flow, you will typically see polyps grow closer to the rock with shorter stalks.
Another is lack of feeding and food as infrequent feeding and low nutrients can lead to an entire colony melting down. You dont need to target feed them as zoas are photosynthetic. It is generally found that target feeding zoas always provides mixed results when a food falls onto their polyps.

Back to parameters, good water quality is a must.
dKH: 8.0 - 11
Calcium: 400 - 480
Magnesium: 1300 - 1400
Iodide: Maintained via regular water changes or manually at small dosages
Temperature: 78-79 degrees
pH: 8.1-8.3
Phosphates: .04 - .09
Nitrates < 10
Temperature and pests are often blamed.