Stylophora dying - almost certainly too late but why?

[Branchie68]

Hi all,

My tank is 3.5 months old and I added this Stylophora 2 months ago. It was doing well, had grown and seemed to be thriving. About 3 weeks ago I noticed that some of the polyps underneath had started to recede. I watched it at different times to see if something was eating them but couldn't find a culprit. Researching further I saw that some people said it may not be getting enough light but it's mid way in my XL 200 Reefer and as I said had previously done fine in that position. I know that water quality is paramount for SPS but again nothing had really changed. It's now got to the point where there is more skeleton than polyps and I don't think it's saveable, but I'd love to know why so I don't make the same mistake again. I've racked my brains but the only changes I've made to the tank recently is to start dosing Mg & Ca. Alk has been dosed for a while. Can anyone think why this might have happened?

Stock:
2 x Clowns
1 x Royal Gramma
1 x Midas Blenny
5 x scarlet hermits
1 x halloween hermit
5 x trochus snails - I think they've bred as there are lots of what look like tiny versions
3 x nassirius snails
1 x strombus conch
2 x stomatella snails
2 x scarlett cleaner shrimps
1 x giant feather duster

Zoas
Clove polyps
Green Star Xenia
Favia
Hammer
Goniopora
Florida Ricordea
Plate coral

I've also regularly added copepods & rotifers and a few amphipods. I'm feeding coral with a combination of phytoplankton and Salifert coral food. All other coral seems happy and growing.

Water:

Salinity - 1.025
Ph - 8.1
Alk - 8 to 8.3
Calcium - 400 to 450 - fluctuations while dialling in dosing
Magnesium - 1275 to 1330 - fluctuations while dialling in dosing
Phosphate - 0.1 approx (Salifert test)
Nitrate - has been steady at 10ppm but last test on 7th Sept was 0ppm

I have been doing twice-monthly water changes of about 15% with home-mixed RODI and Tropic Marin Pro.

I've had a diatom bloom which lasted a few weeks, subsided, came back and is now dropping off again. I'm not sure if it might be the salt as I see there is Silica in it. The blooms also seem to follow new white patches appearing on the CaribSea life rock, so I think that might be linked and the rock is leaching Silicon as it's covering wears away and before I've got any coralline to cover it.

Finally, I'm running a Red Sea RSK 300 skimmer, Matrix and floss in the filter cup with a small bag of Purigen and a large bag of Matrix Carbon in the sump.

Thanks in advance for any help or advice you can give.

Paul

 

[Stigigemla]

I had similar look when nitrate was zero. It can be parasites too.
I would:
1: Doublecheck salinity
2: Add nitrate
3: Dip to check for parasites

 

[Branchie68]

I had similar look when nitrate was zero. It can be parasites too.
I would:
1: Doublecheck salinity
2: Add nitrate
3: Dip to check for parasites

Do you think I should remove carbon or Purigen to get Nitrates up?

 

[Stigigemla]

Carbon does not effect the nitrate so I would keep the carbon in if I can see any advantages with it.
Purigen can bind nitrate so I would take it out.

 

[Graffiti Spot]

I had similar look when nitrate was zero. It can be parasites too.
I would:
1: Doublecheck salinity
2: Add nitrate
3: Dip to check for parasites

Not aware of any common parasites that affect Stylophora and normally I don’t bother looking on the non acro and monti sps.