One type of Zoa dying

[PotatoPig]

I have a few zoas through the tank, and most are doing OK, except for my Rastas.

Two weeks ago they were doing great, and I had colonies of various sizes in three different parts of the tank. One (the smallest) has since vanished, and the other two are mostly, but not entirely, closed up.

The closed Zoas in the largest colony are also browning (this does not blow off them with a turkey baster).

These are also my longest running Zoas, the first batch I added to the tank, been in there over a year now.

All other corals (~30 species of SPS, LPS, Softies, Anemones and other Zoas) are doing fine - brightly colored and growing fast.

Nitrates: 10
Phosphates: 0.1
Calcium: 450
Alk: 9-10
Temp: 77
PAR: Varies by location, they’re generally under about 100ish

 

[Rjukan]

I have a few zoas through the tank, and most are doing OK, except for my Rastas.

Two weeks ago they were doing great, and I had colonies of various sizes in three different parts of the tank. One (the smallest) has since vanished, and the other two are mostly, but not entirely, closed up.

The closed Zoas in the largest colony are also browning (this does not blow off them with a turkey baster).

These are also my longest running Zoas, the first batch I added to the tank, been in there over a year now.

All other corals (~30 species of SPS, LPS, Softies, Anemones and other Zoas) are doing fine - brightly colored and growing fast.

Nitrates: 10
Phosphates: 0.1
Calcium: 450
Alk: 9-10
Temp: 77
PAR: Varies by location, they’re generally under about 100ish

No visible pests I guess? How's your salinity? Can you calibrate however your checking it, if you haven't already?

I had similar problems and salinity was the issue, down around 1.021 and my checker was reading 1.025.. also had an issue with zoa eating asterina starfish.

 

[GSPClown94]

Whatever that micro algae is thats growing on them is preventing them from opening up. Brush it off with a soft toothbrush or paint brush.

 

[PotatoPig]

Whatever that micro algae is thats growing on them is preventing them from opening up. Brush it off with a soft toothbrush or paint brush.

Do you mean the brownish stuff on them?

 

[PotatoPig]

No visible pests I guess? How's your salinity? Can you calibrate however your checking it, if you haven't already?

I had similar problems and salinity was the issue, down around 1.021 and my checker was reading 1.025.. also had an issue with zoa eating asterina starfish.

Salinity is 1.025, checked semi regularly.

No known pests, and everything else - including things that are often picky, is fine.

 

[GSPClown94]

Do you mean the brownish stuff on them?

Yes

 

[PotatoPig]

Yes

It seems to be part of the zoas - like their skin is turning that color. It doesn’t blast off with a turkey blaster or even come off with a toothbrush (soft bristle, but softly and then firmly applied)

 

[GSPClown94]

It seems to be part of the zoas - like their skin is turning that color. It doesn’t blast off with a turkey blaster or even come off with a toothbrush (soft bristle, but softly and then firmly applied)

I’m not sure if it’s an outer layer of tissue or some kind of protective coating but zoas seem to shed this outer layer when algae grows on them. Sometimes they need a little help getting it off, pretty sure that what’s going on here. But if it’s not coming off when you tried to brush it then maybe something else is going on.