I have a large colony of Xenia umbellata, one half of it is doing poorly. The problem started about3-4 weeks ago (very minor), but got bad about 3-4 days ago. I have had it for about 6 months during which it expanded about 10x and I have been selling frags. It is still pulsing, but it is shriveled looking and not getting as big as usual. Also there are some white spots that look like something was eating it. Here are some recent changes/occurances:
-I have an emerald crab that was recently hanging out in the xenia colony 24/7 for about 4 weeks now. I could never tell if he was eating it, possibly piercing it with his legs, but he was definitely stressing it. He is now visiting the refugium as of yesterday.
-1 week ago I removed some large chucks of white sponge from around the base of the colony. The reason for this is the xenia was starting attach to the sponge, the sponge would break off, and my xenia would go on a ride; I did not want it to spread. I was very careful, gently grabbing the large chucks and removing them from the water immediately. Put in fresh carbon for this.
-3 weeks ago I finally got some calibration fluids and realized that my salt was at 1.022, over the course of 3 weeks I brought it up to 1.025. Also found that my PH was 7.8. I have been trying to raise the PH, but I am having a hard time getting it higher than 8.1 (peak).
-There is a green polyp leather upstream from the colony. The side of the colony doing poorly is nearest the green polyp leather. But... the closest 2 pieces to the leather (4-5 inches) are doing fine.
- I did a 20% water change last night and tested all of my parameters:
Alk=10.5 dkh
ca=370
PH=8.1
nitrate= 0-10
nitrite= 0-10
Phosphate=0
ammonia=0
Mg=1500 (high, I need to get another test kit to confirm this)
Water temp 78.9-80.2 over this past week.
Orp= 368, down from 400 3 weeks ago
Salt=1.025
Tank is 55L, 40 gal sump w/fuge, protien skimmer, filter sock, UV sterilizer, carbon.
Lastly, the other corals are doing fantastic, my blue zoos are brighter, my frog spawn is growing, and my calastrea is starting to split (first time I've noticed growth on it in months).
-I have an emerald crab that was recently hanging out in the xenia colony 24/7 for about 4 weeks now. I could never tell if he was eating it, possibly piercing it with his legs, but he was definitely stressing it. He is now visiting the refugium as of yesterday.
-1 week ago I removed some large chucks of white sponge from around the base of the colony. The reason for this is the xenia was starting attach to the sponge, the sponge would break off, and my xenia would go on a ride; I did not want it to spread. I was very careful, gently grabbing the large chucks and removing them from the water immediately. Put in fresh carbon for this.
-3 weeks ago I finally got some calibration fluids and realized that my salt was at 1.022, over the course of 3 weeks I brought it up to 1.025. Also found that my PH was 7.8. I have been trying to raise the PH, but I am having a hard time getting it higher than 8.1 (peak).
-There is a green polyp leather upstream from the colony. The side of the colony doing poorly is nearest the green polyp leather. But... the closest 2 pieces to the leather (4-5 inches) are doing fine.
- I did a 20% water change last night and tested all of my parameters:
Alk=10.5 dkh
ca=370
PH=8.1
nitrate= 0-10
nitrite= 0-10
Phosphate=0
ammonia=0
Mg=1500 (high, I need to get another test kit to confirm this)
Water temp 78.9-80.2 over this past week.
Orp= 368, down from 400 3 weeks ago
Salt=1.025
Tank is 55L, 40 gal sump w/fuge, protien skimmer, filter sock, UV sterilizer, carbon.
Lastly, the other corals are doing fantastic, my blue zoos are brighter, my frog spawn is growing, and my calastrea is starting to split (first time I've noticed growth on it in months).
Good to hear. Also, I have read that the Sarcophyton leather corals and Xenia actually grow better together--this from Mr. Calfo's book where he talks about combining Xenia and Sarcophyton in growout tanks. I have to agree--in my own tank I had a few small Sarcophyton frags, and some time after I added some Xenia and it got a good foothold and started taking off, the Sarcophytons did too. Strange, but true. 
