xenia and zoanthid decline

[alienspacepirate]

Starting last week my little colonies of xenia have shrunk about half normal size and one deflated and perished. However, my zoanthid rocks have been 'melting' for the past few weeks which I believe due to an invasion of red slime algea.

I have some slime algea but only in some very small nickle sized patches here and there around the tank. I dipped my zoanthid and it seemed to help some with some of the algae busing out.

My other corals (brain corals, cyptonite candy cane, mushrooms) are thriving and doing good.

Not that the xenia is really a great coral, I'm just concerned something happened to my water chemistry which could cause the decline. (Like too much phosphorus, etc) I am stepping up water changes (doing 10 gal a week on ~90 gal setup). I do add supplements of the usual flavors. My normal water parameters are good, ph is 8.2 - 8.4.

[hobogato]

problems with xenia usually indicate pH out of normal or pH fluctuation. you may want to double check and use a second testing method for pH. you may also test at different times of the day/night to see how much it is fluctuating.

[allan]

I assume that by normal water parameters are good you are referring to ammonia, nitrates and nitrites... so with that being said.

I couldn't seem to keep xenia. They would melt and fade away, and I was told that they require dirtier water than most of the other corals that you will be keeping. I wouldn't worry too much about that. But the zoas aren't a good thing. I doubt very much that the cyano is what's causing their demise. And the fact that a dip had helped them makes me think that you may have some predator or pest that's molesting them. Are they closed up tight? Or open but shrinking daily?

On a side note, although I've not been able to keep xenia, I do have a small colony of long stemmed semi-pulsing xenia that I've managed to keep successfully. I periodically trim it back but I've not been able to successfully frag them in my system.

Just noticed, you don't have any other zoas that are doing well?

[allan]

dang, forgot about the PH swing. Would that trouble the zoas too?

[hobogato]

maybe if it was severe enough, but it could be two unrelated issues. i would check the zoas closely for nudis or sundial snails.

[alton]

What are your nitrates? Like someone said xenia love dirty water.

[alienspacepirate]

I don't think I have any of the normal pests. But I do have emerald crabs and other hermits in the tank. Perhaps they decided to start munching on the zoas? I did add a new protein skimmer about a month and a half ago. Perhaps it's doing its job and pulling out the nitrates. I'll retest tonight, the other day everything was or otherwise undetectable and the PH is good. I also have a fuge with a lot of algea and run the lights at night to ease the ph swing.

I'm not really caring so much about the cheap coral just worried something in the tank freaked out. I keep hearing now (after research) that hermits and crabs may be munching on the zoas. only about half of the zoa polyps are open and the ones that are have only opened slightly not full bloom. Been like this for a long while now.

[alienspacepirate]

I do have flatworms which love to sit on my mushrooms and suck up my light. I got a wrasse a while ago and he has been slowly making progress. But I can only see them on the mushrooms, not sure why they love to sit on them.

[allan]

If you have them on your zoas, can pretty much count on it, a fresh water dip will get them gone... For a minute.

[alienspacepirate]

Update*

I did a ten gallon water change and cleaned out the fugue. I've ordered a phosphate test because I think that may be my problem, but my nitrite test ran dry so need to pick up another today.

Here are some pics of the coral in question. And when the lights started going low... I found a hermit on top. Now maybe he was just minding his own business, I didn't actually see him chomping on them.. but I plucked his butt out and put him in my secondary tank for now.
11490

Here are the water parameters that I was able to test/calculate last night:

PH 8.2
NO3+NH4 undetectable
KH 5dh
Calcium 500 ppm
CO2/calculated .9mg/L

[alienspacepirate]

11491

Here is with white lights on for reference