Duncans not happy

[Lazydayz]

So this is my first reef tank been doing a lot of reading and needed some experienced help. I noticed 3 days ago my Duncan started acting funny, it closed up and didn't want to eat. So I did water tests with the Salfert test kits I have. All the parameters are good (very steady no swings). Yesterday I noticed the 3 mouths on the right side were wide open. I thought maybe one of the clowns nipped it since they seem to love playing in it. I moved it away from the clowns yesterday. Today I got home and it looks like one of the heads is melting. I don't know if I should let it be, cut that side off or just pull it all together? I'll attach some pictures, also to note it is not my only Duncan the other is fine in the spot next to where the other one was. Perimeters are:
Temp: 80
Salinity: 1.025
PH: 8.2
Alk: 11
Cal: 460
Mg: 1260
Phosphate: .5
Nitrates: 2

This was it last week (the one on the left, the one on right is still doing great):

 

[KrisReef]

Hard to guess why it’s not doing well.
If it got bumped and damaged, or if the clownfish have been tampering with it, if another coral is competing for space with it, or perhaps you have fed it something it could not digest or even just over feeding it, any of these instances or a combination of these could have caused the single head to meltdown.

The parameters are interesting, phosphorus is elevated as is the alkalinity. I’m not sure what is causing your Duncan to act this way?

 

[Jeff Jarry reef]

For some reason I can't seem to keep Duncan's. They don't do well in my tank i have SPS dominant tank. Maybe water to clean I don't know why.

 

[Lazydayz]

Hard to guess why it’s not doing well.
If it got bumped and damaged, or if the clownfish have been tampering with it, if another coral is competing for space with it, or perhaps you have fed it something it could not digest or even just over feeding it, any of these instances or a combination of these could have caused the single head to meltdown.

The parameters are interesting, phosphorus is elevated as is the alkalinity. I’m not sure what is causing your Duncan to act this way?

I know the alk is high I use IO reef crystals always been at 11, everything was happy with it for 2 months now. All the other corals are growing and splitting. I guess I'm more confused on if I should trim off the melting heads or let it run its course for now? All the other heads on it are fine except the 3 on the right side

 

[Lazydayz]

For some reason I can't seem to keep Duncan's. They don't do well in my tank i have SPS dominant tank. Maybe water to clean I don't know why.

No SPS in mine just LPS and softies since I'm starting out too scared to jump in that water still haha.

 

[KrisReef]

I know the alk is high I use IO reef crystals always been at 11, everything was happy with it for 2 months now. All the other corals are growing and splitting. I guess I'm more confused on if I should trim off the melting heads or let it run its course for now? All the other heads on it are fine except the 3 on the right side

I’ve let mine continue growing without trimming injuries without negative consequences, other than the dead heads look unsightly.

 

[Lazydayz]

I’ve let mine continue growing without trimming injuries without negative consequences, other than the dead heads look unsightly.

Thank you for the help! I'll just monitor it

 

[Dave Garrett]

I had to move my Duncan 4 foot away from my clown.... It would try and host it even though it had an anemone...After a year more of growth and on the other side of the tank the clown now goes over a few times a day for 10 minutes or so and fools and rubs the duncan... Now that the Duncan has 30 or so heads... It seems to tolerate the clown for these short sessions... My bet is your clowns are being a bit more ruff then your duncan wants....

 

[Lazydayz]

I had to move my Duncan 4 foot away from my clown.... It would try and host it even though it had an anemone...After a year more of growth and on the other side of the tank the clown now goes over a few times a day for 10 minutes or so and fools and rubs the duncan... Now that the Duncan has 30 or so heads... It seems to tolerate the clown for these short sessions... My bet is your clowns are being a bit more ruff then your duncan wants....

Definitely leaning towards the clowns, caught them over by where it again today! It's a small 29g biocube so can only move it about 10 inches away. Looks a little better, the 3 heads on the right side are goners though.. clowns can be pains but I like the way they look

 

[Jet915]

For some reason I can't seem to keep Duncan's. They don't do well in my tank i have SPS dominant tank. Maybe water to clean I don't know why.

I have the same issue, my sps are growing great, my duncan which ive had for 1.5 years is usually closed.