RFA looks like its melting away

[boeingn747]

So one of my reef tanks this one being a 75gal mixed reef. I have 8 Rockflowers Two or three around 4", one around 3", 3 around 1.5". All but one of them are doing great. I noticed at the beginning of the week that it looked like there was some of the outer polyps (whatever they are called) missing. Maybe a 1/4" section. I couldn't tell if they were gone or just closed up at that spot. Well fastforward to today and I have noticed that it is getting worse to now half or over half is like melting away. Not one of the others show any signs of this. I have watched the tank for over an hr to see if something was picking on it and have seen zero evidence of this. The tank is stocked with several tangs, four lyertail anthias, a couple wrasses, and a aptasia eating file fish. There is also two skunk cleaners, two fire shrimp. A dozen dwarf Hermits. What has me puzzled is the rest look great. Here are a couple pics to show a few of them, to get a idea of what I'm talking about.
Nothing in the tank has changed. Phosphates are higher than I normally keep them as I was a few weeks late switching my gfo out for new. I checked Phosphates lastnight and they were right at .13
Alk is 8.0 on the nuts
Nitrates are around .20-.25
Ph- 8.1-8.3 depending on time of day
Temp 78
Salinity 35ppt

 

[vetteguy53081]

So one of my reef tanks this one being a 75gal mixed reef. I have 8 Rockflowers Two or three around 4", one around 3", 3 around 1.5". All but one of them are doing great. I noticed at the beginning of the week that it looked like there was some of the outer polyps (whatever they are called) missing. Maybe a 1/4" section. I couldn't tell if they were gone or just closed up at that spot. Well fastforward to today and I have noticed that it is getting worse to now half or over half is like melting away. Not one of the others show any signs of this. I have watched the tank for over an hr to see if something was picking on it and have seen zero evidence of this. The tank is stocked with several tangs, four lyertail anthias, a couple wrasses, and a aptasia eating file fish. There is also two skunk cleaners, two fire shrimp. A dozen dwarf Hermits. What has me puzzled is the rest look great. Here are a couple pics to show a few of them, to get a idea of what I'm talking about.
Nothing in the tank has changed. Phosphates are higher than I normally keep them as I was a few weeks late switching my gfo out for new. I checked Phosphates lastnight and they were right at .13
Alk is 8.0 on the nuts
Nitrates are around .20-.25
Ph- 8.1-8.3 depending on time of day
Temp 78
Salinity 35ppt

The one you refer too looks like it has an injury or stung by something nearby
They require light for their cells and production of zooxanthellae. At the tank level they’re at, I doubt too much light
What is your nitrate and phosphate level?

 

[boeingn747]

The one you refer too looks like it has an injury or stung by something nearby
They require light for their cells and production of zooxanthellae. At the tank level they’re at, I doubt too much light
What is your nitrate and phosphate level?

I listed the parameters in my post near the end but the phosphates are .14 and my nitrates are .20-.25
As far as getting stung, there is just nothing around or near them that would do that. There is a bta near there but back on the otherside of that rock and it has been in the same spot for over a year.
Is there a pest that might not be visible or that I am not seeing that would be doing this? Or can you maybe give me an idea of what kind of thing could be doing this to it?
As far as lighting goes, they are at the bottom of the tank. The par at the bottom is around 100. Now some of them are at 100 par and some are tucked kinda up under some rock overhangs, so not getting 100 but Definitely getting enough light I would think, plus I am spot feeding them all once and then twice a week alternating. One week once, next week twice, etc. I will give them whatever I am feeding the rest of the tank and/or corals.

 

[Uncle99]

The Aptasia is an anemone, along with your RFA.
A taste by your filefish?

 

[boeingn747]

The Aptasia is an anemone, along with your RFA.
A taste by your filefish?

I mean I guess! It's a thought. I have 2 reef tanks and 2 fowlr, I have a aptasia eating file fish in 3 of the tanks of those one eats aptasia, and not the one in this tank. I am constantly watching the tank looking for the culprit. The filefish in this tank has been in there for 3 years. He has never touched a coral polyp or a aptasia, at one point this tank was full of them too. As much as I would love to know what it is. I just don't think it's the file fish.

 

[boeingn747]

Here are a few pics to show more detail. Not sure that will help, but maybe.

 

[vetteguy53081]

I listed the parameters in my post near the end but the phosphates are .14 and my nitrates are .20-.25
As far as getting stung, there is just nothing around or near them that would do that. There is a bta near there but back on the otherside of that rock and it has been in the same spot for over a year.
Is there a pest that might not be visible or that I am not seeing that would be doing this? Or can you maybe give me an idea of what kind of thing could be doing this to it?
As far as lighting goes, they are at the bottom of the tank. The par at the bottom is around 100. Now some of them are at 100 par and some are tucked kinda up under some rock overhangs, so not getting 100 but Definitely getting enough light I would think, plus I am spot feeding them all once and then twice a week alternating. One week once, next week twice, etc. I will give them whatever I am feeding the rest of the tank and/or corals.

Phosphate is elevated and should be range (.04 - .06).
im not sold that the lighting is the issue and phosphate a small maybe
Look underneath for any pests but I’m thinking a sting.
slso assure temp and salinity remain in normal range

 

[boeingn747]

Phosphate is elevated and should be range (.04 - .06).
im not sold that the lighting is the issue and phosphate a small maybe
Look underneath for any pests but I’m thinking a sting.
slso assure temp and salinity remain in normal range

I understand that most reefers try to keep phosphates low .04-.08 being what most would call ideal. In my other reef tank I have no problem keeping phosphates at .06 all day everyday. This tank has just always ran high. It is very heavily stocked with fish and coral, inverts. A lot of the fish in this tank will ultimately end up in my big reef tank when they out grow this tank, maybe then the phosphates will come back down. I seem to always be at or near .1-.15 in this tank. I have no problem growing coral in this tank and despite having a decent sized refugium growing several types of macro, and running rox .8 carbon, along with gfo in a separate reactor, I struggle with lower phosphates. I've come to terms with it and contribute the elevated phosphates to the heavy bioload. I would love to know what is stinging it. Only think near it and that's within 4" is a random soft coral frag and a rhodactis mushroom. There is also 3 zoas that popped up right next to the nem. I no I have don't have your experience level, and would trust 99% of what you said. I do consider myself an experienced reefer and the thing that bothers me the most about this hobby is not knowing. Most stuff makes sense when you follow the crumb trail. This has me genuinely puzzled.
What's the chances that there is something under it that it bothering it? With the nem buried into a rock crevice, how will I ever get under it to find out?

 

[boeingn747]

Phosphate is elevated and should be range (.04 - .06).
im not sold that the lighting is the issue and phosphate a small maybe
Look underneath for any pests but I’m thinking a sting.
slso assure temp and salinity remain in normal range

I forgot to mention that I have 3 urchins in this tank a small tuxedo 1" and 2 Halloween urchins. Any chance that one of them has rolled by the nem and irritated it? Only other thing i can think of.