Zoanthus hardening

[DusanP]

Dear All,

I need your help.

I have a problém with Zoanthid Hardening.

It mainly happens to some of my Paly (green people eaters) but also for some classic zoa as Rasta.

They look good, but some pcs from the colony close, and they become hard.

I tried to clean it by brush, I tried to dip it in iodin, I tried to use peroxid dip, and I tried to skin off the skirt (Impossible to do – it is not only on surface – when I go deeper I kill it it seems that whole skin become hard), but it did not help. No idea why this can happen and what causes it.

I have a 600l tank, I have about 50 species of zoas.

My parameters are:

The tank is 3 years old. Fully loaded mix of LPS, Soft and some SPS.

I do regular water changes twice a week – in total, cca 10% weekly.

KH – 7,3-7,6 quite stable.

PO4 – 0,01-0,03

NO3 - 12 – 18

Salinity 35 ppm

Calcium – a bit lower – 380 – 420 (I did not calibrate Hanna ). Now I am trying to fix it on 420-450

Magnesium – 1400

I dose regularly Iodin and I am on the ideal level according to ICP.

I am running Zeovit systém with zeolit filtr.

I am doing regular ICP once a month.

No pox, no zoa spider.

Regular flow over them.

Target feeding once a week by Zoa food.

Radion gen 6 – blue and Pro combination, program AB+

The only issue I can see from ICP is that i have high Iron (Fe) – about six ppm- due to the corrosion of my stand. This was fixed one and a half months ago, and I did several 20% water changes a week.

The „stoned“ zoas stay a couple of weeks, but then they die.

Any idea what can cause it?

Many thanks

 

[Mr. Mojo Rising]

All that text but no pictures? Pictures really help sometimes...

 

[DusanP]

All that text but no pictures? Pictures really help sometimes...

Hi, here are some. it is not a perfect photo, but I hope it can help identify the problem.

Unfortunately, rastas already gone. These are the People eaters and the petroglyphs. the algae you can see on the surface is a secondary issue - when it gets hard, it comes later. It is surely not the root of the problem.

 

[Mr. Mojo Rising]

If you have one, grab a magnifying glass and have a close look for critters such as aptaisia, hydroids, small snails, cloves, etc.... My first guess is that something is growing in there, or something is eating them.... Sexy shrimp eat zoa's.