christmas rock -- porites are receding slowly

[CTaylor]

I have a xmas rock which I've had for over a year now. It was doing fairly well for the first 7 months. After that time it slowly started to recede.

*Can I do a dip of some form to try to halt this? What should I do? It is a brown variety of porites. All the worms are still doing just fine. It looks like it likes very high lighting, so I have it 1/3 down the tank (as close to top as I can get).
It's now under 36 LEDs of half royal blue, half 10k white. 65 gallon tank, Ca is about 385 now. Going up slowly. pH 8.2. Temp 83. Near 0 nitrate, phosphate. I dose Strontium and Molebdenum, as the corals seem to like it.


Background:
I believe part of the reason may have been bad lighting (under a 250 watt reef Lux 12k - or 14, I forget, halide). A few of my corals went down hill and died when this one started receding in January. It also may have started because I was using a DI cart in my RO DI that was giving off a fish odor (melamine, or something like that). I changed as close to 100% of my water as possible. It looked better after. Still since then it's been slowly receding.

Side note is that I have two little RBTA and pulsing xenia that never looked too great.

In mid July I did a 35% water change, I changed out my shallow sand bed of coarse sand for oolitic, and I updated the lights... I have now 36 LED's from RapidLed (half royal, half white).

The xenias are pulsing wildly now, the RBTA's are somewhat bubbly and nicer.. Everything is looking good now. The remaining porites are extending nicely. But it is still slowly receding.

I've had a greener porites/xmas rock a long time ago that I kept for 5 years, which grew a lot. So I don't know what it wrong here.

[Dog boy Dave]

Its going to take several months for your tank to stabilize after changing sand beds. It can also take months for your corals to recover from a period of chronic stress like yours have been subject to. Long term stability with high water quality and your corals will recover and thrive. If they do not thrive, then your water quality still needs work. Get that right and it doesnt matter what lights they are under as long as they get enough intensity. Do you do regular water changes now or was the 35 percent just a one shot thing?

[CTaylor]

I was wrong, it was over 50% water change. I do 20-25% monthly. The tank is lightly loaded with life as well (all I have is listed above + 2 oscellaris and 2 neon gobies).
The "sand bed" was at most 1/2", likely less. I had one in my previous set up and from that set up I just didn't like they way this one looked. It clumped into rocks really easily and it was just too coarse. Always looked dirty as well. So I changed it to the same type I had before -- oolitic small grains. Still 1/4-1/2" overall. So the tank is based mainly on the live rock.

The life in the tank is doing fantastic. I don't think things have to settle too much given that. I'll take pics of the corals to show. An example though it my crazy beating xenias. I don't think they pulse intensely in anything less that good conditions (right?). My elegance is doing amazing, hammer also. I know they are not SPS, and SPS are more temperamental.

Anyhow,I'd like to dip the porites to save them. It's like an STN that acros get sometimes. It is not receding on the very top of the rock. There seems to be a growing edge on the top. But there are spots of recession in the middle and toward the lower part of the coral.

Should I do iodine? Is there a recommended dip/recipe?

Thanks again

[Dog boy Dave]

I wouldn't dip it. Keep up on your water changes. Dips dont help unless you are targeting a specific pest. Last thing you want to do is stress this coral even more. Maybe double up on your water changes. Not twice as much, twice as often.

[CTaylor]

It's growing back! I took pictures of it about 6 weeks ago. So I could tell how much it's receding over time. I compared the pics to today. Its actually more today then back a few weeks ago. I saw what looks like a growth line on much of the bottom edge, and a strip of lighter polyps on the top edge. They are both new growth areas. It spread a few millimeters since the pics.
Changes over the past two months:
Main things:
*I have it as high in the tank as possible now (which is still 8+ inches under water surface).
*LED lighting replaced a ReefLux Halide.
*I directly feed the coral and xmas trees every other day with pulverized fish food (which the fish also eat or other frozen food mashed up)

Other I did 6-10 weeks ago:
*I changed out my course sand bed (not much, but maybe 1/3" total on bottom of tank) with oollitic fine sand.
*Water changes (but that's not new)
*In the last week I realized my salinity was too low (1.022-1.023 -- my refrac was calibrated on DI water, not known 35 ppm salinity). So this was raised in the last week. I don't think this new growth was in one week, though.

I've had this over a year now, and I'm happy that it looks like I'm able to finally keep this healthy and growing.

I'm glad I didn't dip it (yet). Though if I did it will be Coral Rx

[CTaylor]

I'll have to post before and after pics. I'm so happy about its recovery. It seems like a cm growth front per month. (The growing edge of the coral is re-covering dead rock like a lava flow spreading outwards.) I can foresee it eventually spreading onto other rocks (to frag I guess). Pics coming if anyone's actually interested lol. Oh and the xmas worms are all still alive and well (1 year and 4 months since I got them).

[Dog boy Dave]

I'll have to post before and after pics. I'm so happy about its recovery. It seems like a cm growth front per month. (The growing edge of the coral is re-covering dead rock like a lava flow spreading outwards.) I can foresee it eventually spreading onto other rocks (to frag I guess). Pics coming if anyone's actually interested lol. Oh and the xmas worms are all still alive and well (1 year and 4 months since I got them).
Well done, another coral saved from the deadly dip.