Duncan coral not opening

roblesreeef

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Hey everyone, I’ve recently had one of the heads on my Duncan coral close up. It’s been closed for about 5 days now and I’m not sure what to think. My parameters seem to be ok, so I’m not sure what I’m doing wrong

Magnesium: 1280
Calcium: 480
Alkalinity: 9
Phosphate: 0.02
Nitrate: 20
Nitrite: 0
Ammonia: 0
Ph: 8
Salinity: 1.024
20251219_131444_53D62002-8723-4A2C-838A-5D2E96DFE541.png

20251219_131444_D607FF35-24CC-4C5C-9414-B259DDB2E212.png
 
How long have you had it? I added my first duncan coral -- one head -- when my new tank was about three months old. It opened and closed for a couple weeks, two new heads started budding , and then it closed up tight for like two months. I thought it was dying, though the stalk always remained bright green. About a month ago it opened back up with long tentacles streaming in the flow and has looked great ever since. It somehow sprouted a fourth head without me even noticing for a couple weeks. They have a reputation of being temperamental, and mine has been as advertised.
 
How long have you had it? I added my first duncan coral -- one head -- when my new tank was about three months old. It opened and closed for a couple weeks, two new heads started budding , and then it closed up tight for like two months. I thought it was dying, though the stalk always remained bright green. About a month ago it opened back up with long tentacles streaming in the flow and has looked great ever since. It somehow sprouted a fourth head without me even noticing for a couple weeks. They have a reputation of being temperamental, and mine has been as advertised.
I’ve had it for about 2 months now. I also got mine around 3 months after setting up the tank, so maybe mine is doing the same thing
 
How's the flow? the polyps should sway in the flow, IMO medium light and medium flow
 

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