Is Rock Flower Nems Dying? Tentacle melting issue

[Trueruby]

Hi Everyone
I got 14 rfa in my 150 g tank

recently two of my beauty started to loose tentacles. It is obviously rotting and falling a part. Does anyone ever had something like theese? Please see below pics and tank parameters
First I tought they get too
salinity 1025
Temperature 24.5C
Ca 415
kH 8.5
Mg 1475
Phospate 0.03
Nitrate 1-3 ppm
PH around 8.25
I have no papermint shrimp or filefish

fishes I have ;
Naso tang
Scoppaa tang
Yellow tang
Pyramid butterfly
Yellow wrasse
Cromis
Mandarin dragonet
Clown fishes

sea cucumber.

Click here to see the video

Second video you can see slimy things on it

 

[Timfish]

How long have you had them? Even if you've had them a couple months it's still possible they had an issue when you got them. You PO4 is just marginally acceptable and I would raise it. FWIW .03 mg/l is the minimum, .5 mg/l is acceptable and even .9mg/l might not be an issue.

 

[Trueruby]

How long have you had them? Even if you've had them a couple months it's still possible they had an issue when you got them. You PO4 is just marginally acceptable and I would raise it. FWIW .03 mg/l is the minimum, .5 mg/l is acceptable and even .9mg/l might not be an issue.

Its been around 2 months. Po4 will rise slowly in time due to incresed feedin of fishes. Do you know if I can dip rfa in iodine or something?

 

[Timfish]

You can try but I wouldn't, just keep an close eye on them if you do. If most are looking good and most of your other corals look good odds are they just didn't acclimate well or they had some other issue before you got them.

 

[Trueruby]

You can try but I wouldn't, just keep an close eye on them if you do. If most are looking good and most of your other corals look good odds are they just didn't acclimate well or they had some other issue before you got them.

The rest off the corals are all good. I have quite full tank. The rfa night in 2 days. Just melted away, the second one is fighting ıts been more than a week but about to lose the war. I will try dipping iodine