Another case of Zoas with the umbrella syndrome (pics of progression included...)

DoctaReef · May 6, 2020

So im watching one colony of my Zoa's go from looking great to bad over the course of a week or so. Here is what they looked like on 3/28/20:

And here is what they looked like 5/4:

And today:

I checked my parameters:
Salinity: 34.2 (Apex) 34 (Refreactometer, calibrated yesterday) Full disclosure, It had been running low (32?), I've been inching it back up.
pH: 8.18 (Apex)
Ca: 389 (Trident) 390 (Red Sea) 400 (2nd Red sea, different batch)
Kh: 8.34 (Trident) 8.4 (Red Sea) 8.7 (Red Sea #2)
Mg: 1397 (Trident) 1350 (Salifert)
PO4: .36 (Hanna)
NO2: B/w0 and 2 on the Red sea kit.... I don't have a ultra low NO2 kit...

A few other thoughts:
This is a RSR 425XL- about 100 gal system volume.
I use Tropic Marin Pro Reef.
My water goes through a BRS 7 stage RODI. changed the resin a few days ago to be sure that wasn't an issue.
I run a BRS Carbon reactor, changed the carbon maybe a week ago, but I've been running carbo since the tank was set up.
I do AWC through the Apex every night- 1.5 gal.
I do Trident Controlled dosing of Kh, Ca and Mg.
99% of my other corals seem fine, including other Zoas, acros, montis, Blastos, Favia, Acans, Chalice... the only other coral that has recently looked sketchy is a neon trumpet coral that has lost some tissue on one of its heads (lower right):

Not sure what to do? Any thoughts?

nex64 · May 6, 2020

Salinity swings?
You said you were inching it back up but it could be your culprit.

DoctaReef · May 7, 2020

nex64 said:
Salinity swings?
You said you were inching it back up but it could be your culprit.

Less of a swing... more constant at 32, recalibrated, and pulled it back up... I use a neptune ATO, so i have pretty tight control over salinity, so long as the readings are right. Im not sure the salinity is the culprit... I've got so many other corals that are doing awesome.

Red Leader · May 7, 2020

When mine did that I used Chemiclean and they were fine in 3 days.

DoctaReef · May 7, 2020

I'm thought that vermitid snails might be bothering them, but now I'm concerned that I might not be looking at Digitate Hydroids...

Joiningsession · May 7, 2020

Red Leader said:
When mine did that I used Chemiclean and they were fine in 3 days.

Chemiclean dip? Or the 2 days then WC? Been tempted to try this for a couple frags that struggle.

Red Leader · May 8, 2020

Joiningsession said:
Chemiclean dip? Or the 2 days then WC? Been tempted to try this for a couple frags that struggle.

2 days then WC. Several zoas were showing various umbrella-ing symptoms.

danschoenherr · May 8, 2020

Ive had this happen over the years and they do usually return to normal in a few days or so. Just recently, Ive been starting to watch for this after I change out the carbon. I only run a bag in my sump and only change it every other month . My thought is that the fresh carbon clears up the water so quickly, that the light penetrates more and may "shock" the polyps, thus resulting in the "umbrella" effect. I should have some more to add in a few months, as long as I remember to look for this after carbon changes.