RTN in LPS?

[russell.dexter]

I have a 36 gallon bow mixed reef that has been up and running for two years. I used all live rock at set-up so never experienced much in the way of an initial cycle. For months I battled what I thought was dinos- but after checking with a microscope I discovered was chrysophytes instead. Regardless; after repeated testing I realised that the primary cause of the issue was zero phosphate / nitrate that I could not raise no matter what I fed in the way of reef roids/ frozen / flakes / pellets etc.

Enter Brightwell Phosphate and Nitrate that I dosed at the recommended rate, along with adding a sump to get more flow - I finally got rid of the algae.

Even while dosing the products I would only register the minimum on my test kits (dosing 5mls daily of brightwell's nitrate resulted in a nitrate reading of less than 20, 5mls of phosphate resulted in a reading of 0.01.) I utilise Hanna's low range test for phosphate and both salifert's and nyo's for nitrate) I ran out of product several months back and noticed;

All coralline algae on the back and side glass bleached and died
Two sps sticks paled and receded
Soft coral growth stopped.

Test results of course showed 0 phosphate and nitrate so I resumed dosing

About one week ago I noticed a small area of discoloration on a rose coral (Manicina areolata) and realized that half of the flesh on the coral was gone. The coral seemed to be covered in a brown goo with pieces of flesh flowing in the current. It looked exactly like what I have seen with RTN in SPS corals. It was clear that the coral could not be saved so I immediately removed it from the tank. Over the course of the past week I have lost colony after colony of rose corals and acans- in fact I only have one left in the tank. I swapped out the carbon and performed a water change but it seems to not have made a difference. SPS and soft corals have so far been unaffected.

Water testing showed;
ALK 9.2
PH 8.0
Mg 1400
Ca 410
Nitrate: 10
Phos: 0.01

I ran a sample to a LFS and the results were similar on the spin disc and I have included a photo below.

Any ideas on what may be killing all my LPS?

Or why I cannot seem to raise my phosphate? I have increased dosing to 10mls per day of Brightwell's neophos and am considering putting it on a doser to dose the amount over the course of the day to see if that can help with my coral colours/ growth

I plan to upgrade to a 40 breeder in a week or so- the form factor of the 36 bow does not lend itself well to reefing

Tank setup:
36 bow display with a 20 gallon sump. HOB overflow with filter floss. I do run carbon as I have soft corals.
2x Nicrew 50 watt lights

Inhabitants:
Two emerald crabs
BristleStars
Sand Sifting Star
Two Ocellaris ClownFish
One Beau Gregory Damsel
Four large Cittarium pica
Two Blue leg hermits

 

[tbrown]

Look up "Brown Jelly Disease" and see if that's it. Sometimes it spreads, sometimes it doesn't. I suppose it depends on what caused it.