GSP and Duncan Questions

[andiesreef]

1. My duncan coral has this hole-type thing at the base of its left head. What is it? Is it branching? This is my favorite coral and I don't want anything to happen to it

Seems super healthy. Fed every other day with leftover brine shrimp or pellets and has been popping out tiny heads like no tomorrow. Located in medium-high light and medium flow.

Parameters:
Temp: 81 degrees f
Salinity: 1.024
Ph: 8.2
Phos: 0.25
Nitrates: 10ppm
Ammonia: 0
Nitrites: 0
Calc: 380
Alk: 7.7
Mag: 1300ish 2 weeks ago (I don't test mag too often, maybe once a month)

2. My GSP is slowly melting away. I'm so confused. Parameters seem ok. It was located in low flow and low light before it closed up about a week ago and I dipped it. A few days later I moved it up to higher light and flow to no avail. Scrubbed it off with a toothbrush today and half the colony fell away. I feel so stupid for killing a "noob coral". What am I doing wrong? Same parameters as above, was doing fine for months before this happened. Was one of my first corals. The zoa I bought at the same time is doing fantastic along with all my other corals.

 

[T-J]

When you say "newish", how new? Looking at your sand, it looks really new. Your phosphates are pretty high. LPS do like dirtier water, but that's still pretty high. Also, what kind of light is on the tank? Oh, and what size tank are you working with?
Not sure how you are killing GSP. Perhaps the dip and scrub was a bit much.
I don't want to freak you out, but I'm a bit concerned about the discoloration on the Duncan. Looks like bare skeleton to me, but it's kinda hard to tell in the pic. On the far right side it looks like a skeleton just below the one head. I have a rather large Duncan colony, and it's flesh is smooth and all the same color down the stalks.
Can you get better pics?

 

[andiesreef]

When you say "newish", how new? Looking at your sand, it looks really new. Your phosphates are pretty high. LPS do like dirtier water, but that's still pretty high. Also, what kind of light is on the tank? Oh, and what size tank are you working with?
Not sure how you are killing GSP. Perhaps the dip and scrub was a bit much.
I don't want to freak you out, but I'm a bit concerned about the discoloration on the Duncan. Looks like bare skeleton to me, but it's kinda hard to tell in the pic. On the far right side it looks like a skeleton just below the one head. I have a rather large Duncan colony, and it's flesh is smooth and all the same color down the stalks.
Can you get better pics?

My tank is about 4 months old. It has gone through the initial cycle and the diatoms/cyano. It's fallow right now and is filled with pods. Coralline algae is beginning to grow. My sandbed is now peppered with some algae as it ages (and I plan to clean it soon). I've got a Current Marine Orbit LED and the Duncan has been situated a few inches under it for about a month. My phosphates are high, yes, but I only keep hardier LPS and softies so I'm not super worried. The tank is a 20gal long.

Yeah, I see how the pic looks pretty barren. I think it's mostly the glare from the tank. I'll try to take more pics tomorrow, but IRL it looks like a brown, iridescent green-tinged base and I believe the hole could be the inner skeleton?? Again I'm not at all sure and came here for help

As for the GSP, it wouldn't open so I dipped it, it continued to deteriorate, so I scrubbed it, and now we're here.

 

[Jekyl]

Get the GSP off of your main structure. If it does start growing it will take over everything. If it were me I'd burn it, but that's because I made this mistake before.

 

[andiesreef]

Get the GSP off of your main structure. If it does start growing it will take over everything. If it were me I'd burn it, but that's because I made this mistake before.

Forgot to mention I usually have it on a tiny island, just moved it for better flow and light .

 

[Jekyl]

Forgot to mention I usually have it on a tiny island, just moved it for better flow and light .

Get salinity to 1.026, temp to 78. Otherwise there's nothing else I see off. Your tank does look pretty brand new. At that stage corals are hard to make thrive. Nothing kills GSP. I've flipped rocks over, blasted it with light and flow, I even dump buckets on it during water changes.

 

[andiesreef]

Get salinity to 1.026, temp to 78. Otherwise there's nothing else I see off. Your tank does look pretty brand new. At that stage corals are hard to make thrive. Nothing kills GSP. I've flipped rocks over, blasted it with light and flow, I even dump buckets on it during water changes.

My tank is 4 months old, so still new. I'll tinker with the temp and salinity tomorrow. It has a few corals in it but this Duncan was the first one to really start thriving. It along with coralline algae and other corals growing have begun to deplete my calc + alk so I've been dosing small amounts of Brightwell to keep things stable but I admit I've slipped a tad with daily alk and calc monitoring. Obviously because of this my tank is not super stable yet and I'm still figuring out what the tank needs to thrive. This is my first reef tank so I really want to do things right here.

 

[andiesreef]

Get salinity to 1.026, temp to 78. Otherwise there's nothing else I see off. Your tank does look pretty brand new. At that stage corals are hard to make thrive. Nothing kills GSP. I've flipped rocks over, blasted it with light and flow, I even dump buckets on it during water changes.

When you say "newish", how new? Looking at your sand, it looks really new. Your phosphates are pretty high. LPS do like dirtier water, but that's still pretty high. Also, what kind of light is on the tank? Oh, and what size tank are you working with?
Not sure how you are killing GSP. Perhaps the dip and scrub was a bit much.
I don't want to freak you out, but I'm a bit concerned about the discoloration on the Duncan. Looks like bare skeleton to me, but it's kinda hard to tell in the pic. On the far right side it looks like a skeleton just below the one head. I have a rather large Duncan colony, and it's flesh is smooth and all the same color down the stalks.
Can you get better pics?

After more research I think I probably fed the Duncan coral too much - other people have seemed to have similar issues where tissue growth outpaces the skeleton after overfeeding and these kind of holes form. Sometimes it seems to be followed by rapid tissue necrosis which I'm hoping does not happen here. Hopefully I can keep parameters stable, stop feeding for a while, and pray that it recovers. Any tips on what else I should do?