Xenia tissue deteriorating

[pat8you]

So i've had this xenia in my tank for a couple months now and this has been an issue for a while. I started a thread a while back and people said that it just looked like new heads were coming in so i waited it out and figured i would see what happened but I'm concerned that there is something else wrong with it. There seem to be places where the tissue on the base is eroding from something. A few days ago i noticed that in one place there was something green on the tissue that i assume is algae. I'm just not sure whats going on here. The top seems very health and continues to grow new "arms" at an alarming rate. Here are some pictures.

The green stuff is circled in red and the other places were the tissue is scarred is in blue.

Water parameters:
SG - 1.022
ammonia - 0
nitrite - 0
nitrate ~ 20ppm
PH - 8.2

The only thing i add to the tank every once and a while is a PH buffer to keep the PH and alk up. Salt water is pre-mix from the LFS and is made with RO/DI. I know the nitrates are a little high (not an accurate reading still using the strips) but even with only feeding every other day what the fish finish in about 45 sec and PWC weekly around 15% i can't seem to get them lower. Just not enough water volume and no place to put a skimmer in. My other tank info is in the signature. I think that should cover all the usual questions but feel free to ask anything else. Thanks

 

[ccCapt]

I would suggest buying a test kit and not using strips. They are generally very inaccurate. 20 nitrate is on the high side and could be higher with a better test kit. Since the lfs is making your water, do you know what kind of salt they use and how often they change membranes, filters and resins in their RO? Have you tested their water before adding it to your tank?
You mentioned you add buffer for your pH and alk. What is your alk reading? What exactly are you buffering with?

 

[cmor1701d]

Same questions here. I have to prune my xenia regularly or it will take over the tank. I've had it seem to die back or shrink for a while then it comes back again with a vengence.

 

[pat8you]

I'm not sure what salt they use or how often they change their RO/DI stuff out. I've never tested it because all i have is the strips and like you said they can be pretty bad. I need to get a better nitrate test but i'm an extremely poor college student and i've been putting it off. This is the buffer i use. I only add it when i get a new bucket of salt from the LFS so about every 3-4 water changes. I typically add less the recommended amount. Alk looked to be about 220 but again thats the strips. Next time i go to the LFS i'll see if i can find out what salt and how often they change out the RO/DI parts.

 

[MarineFlake]

Potentially something stinging or nibbling. My xenia look like that when they grow too close the galaxy coral. The galaxy in turn reminds the xenia of its boundaries. I did have a crab a while back that had a taste for the xenia. Thankfully, nature took its course the crab is no longer with the living. So many things it could be, the best advice so far is to test, specifically alk and iodine levels when it comes to softies. They do not have the same thirst for CA as their LPS/SPS relatives. If nothing else, simply rip one off a rock and place it into confinment or place something around it to protect it. That way if something is bothering it, you should see a difference between the protected 'control' and the rest of the xenia. In either case, don't fret, if you get it figured out too late, most people would gladly pass on more xenia to you.

cheers

 

[pat8you]

The only other coral i have thats even close is a small duncan colony and i was having these problems before i put that in. The crabs could be a possibility. I've never seen them go by it but i will watch for that i guess.

 

[pat8you]

Should i try and scrape off the green stuff on the one or just leave it and see what happens?

 

[pat8you]

I checked with the LFS today and he said they changed the cartreges once a month and the resins when ever they start to show color. He said they usually maintain 0 TDS. Not sure what to do. I've been watching and i haven't seen the crabs or snails go anywhere near the xenia to be nibbling on it. I'm out of ideas

 

[ccCapt]

I was at a presentation today by Kevin Kohen, director of Dr F&S Divers Dens. He talked about the import of coral and the pests that come with them. There are soft coral eating nudibranch's, and some of the pics he showed looked just like your pic. Exam it closely at night with a flashlight after the tank lights have been out for about an hour. They blend in unbelievable well with the coral.

 

[pat8you]

What should i be looking for when i check it over? is it like a bug or something?

 

[ccCapt]

Try a Google image search for nudibranch. It would probably look just like the feathery ends of the xenia.

 

[pat8you]

I looked at it with a pretty bright lite after the tank lights had been out for a while and didn't see anything. How small are we talking here? like 2-3mm or size of a pen tip? All the ones on the google search came up very bright and colorful and i would have noticed something like that. can they change colors?

 

[pat8you]

i did a search for nubi and xenia and found this link. The little thing looks almost exactly like xenia. not sure i would have seen that. i guess i will look again tomorrow and see if i can find anything.

 

[ccCapt]

It's amazing how nature works. Quite the camo job I'de say.