Dan's 40 breeder, having issues

[dan40b]

Hi everyone, new to the site but have had my mixed reef running for about nine months. I've been having issues lately with what I believe is stn. About a month ago I got a couple chalice frags that almost immediately started to recede after entering my tank. I also have a long tentacle plate that is showing some skeleton. The chalices are both completely void of flesh but the plate seems to have only lost a little and is holding strong. All my parameters seem to be in check. The rest of my coral seem to be doing alright.
some background on my set up. 40 breeder with a 40 breeder sump, chinese led light, bubble magus curve 5 protein skimmer. I have a refugium in the sump but recently changed to an ats. Stock is 2 clowns and 2 purple fire fish. I also have a dottyback living i the sump because he killed a goby and several inverts.
parameters
alk: 7.5 (hanna chercker)
phosphate: .02 (hanna checker)
calc: 453 (hanna checker)
mag: 1350 (salifert)
ph: 8.1-8.2 (salifert)
nitrates: .0-.01 (salifert)

Im open to any thoughts or suggestions. Thanks, Dan

 

[Reefing Madness]

 

[MrDJeep123]

When you placed them in your tank where did you place them? Top, middle, or bottom? If they were to high in placement near the lights, they would do that. That would be my guess. The LEDS are very powerful and if most corals aren't acclimated to the light, death can become them.

 

[dan40b]

I had them all on the sand bed. I learned my lesson the hard way with leds. I fried a trumpet and bleached a hammer. I dipped the long tentacle plate in coral rx a few days ago and it seems to have at least slowed the necrosis. It's just find it strange that the ltp started this after months of being fine. I'd think the chalice brought something into the tank but I dipped them (and all corals) before I put them in.

 

[MrDJeep123]

I had them all on the sand bed. I learned my lesson the hard way with leds. I fried a trumpet and bleached a hammer. I dipped the long tentacle plate in coral rx a few days ago and it seems to have at least slowed the necrosis. It's just find it strange that the ltp started this after months of being fine. I'd think the chalice brought something into the tank but I dipped them (and all corals) before I put them in.

How long did you have them before this issue occurred? I was under the impression they were new additions.

 

[fishroomlady]

I think your alk could be bumped up

 

[dan40b]

The chalices were new the ltp I've had for 3-4 months.

You can kind of see the skeleton along the bottom. It's just on the one side of it.
In regards to the alk, I've been trying to keep it around 8. I've been using bicarbonate solution from brs.