1. Type & how long you have had it: Galexea for 1 year
2. Current lighting & Bulb Age: Tao dimmalbe LED I setup 2 weeks ago, dimmed all the way down
3. Nitrate: 0
4. Calcium: 420
5. Phosphate: .05
6. Alkalinity: 13dKH
7. pH: 8.2
8. Salinity: 1.026
9. Temperature: 78*
10. Liquid or strip test kits: liquid API
11. Location in tank: sand bed
12. Current amount of flow: high turbulent flow, probably in the neighborhood of 850 gph at his location
13. Current tank dosing regimen: Typically I do 10mg seachem marine buffer weekly after the water change and 10 ml CA and 5 ml alk. But recently my Alk was really high (15 dKH) and CA was on the low side (360) so I was adding CA Chloride at 15 ml per day Sun-Tues this week until It was the readings above yesterday (wednesday) (This is what I believe to be the issue.) I also add 3-5 drops of iodine once per week I've been reading articles and threads on the benefits.
14. Nearby coral: none within 10 inches and those were Zoas and Palys, this guy hasen't sent out sweepers for a good 4 months though. Plus he would win any battle with those other species...
15. Explanation of problem: It is totally bleached and all of the polyps are receded, some are completely gone...
About three weeks ago I had a similar issue with it, didn't look quite as bad as this and it was higher up in the tank, about 6" off the sandbed and in a higher flow area and I had the powerheads on alternating schedules like 3 hours a time so it would get a lot more laminar flow than turbulent. I also added the new LEDs so I figured it could be either the light or the flow so i moved it to the SB and left the powerheads on all the time and it started coming back- it regained all of its color and the tenticles were beginning to grow and come out all the time.
Then just yesterday I saw it and it looked totally white again so i thought maybe still too much light, but doubt that- I moved it to a shadier spot half under a rock and two peppermint shrimps jumped on and started picking whatever they could from the completely receded polyps so in an attempt to keep it from constant harrasment I moved it to a frag rack that is half way up under an overflow box. like the shrimp can't just swim up there but no other options...
One other thing that I have done differently that could be the problem is I bought some coral frenzy and started feeding the corals twice a week with a turkey baster and I noticed the shrimp (1 cleaner and 3 peppermint) would crawl all over every coral and steal the food from their mouths.... I think this really annoys the galaxea coral and may be the issue. And I did the coral frenzy the night before (Tuesday night)
FInal observation is every other coarl in the aquarium is doing great. I've been working hard to get phosphates lower and feel like I've finally turned a corner (I know the coral frenzy doesn't help with that so I've decreased that to once a week.)
So I have 3 possible issues going on which represent things that have changed in the tank:
1. new lighting, flow
2. changing the dosing to lower alk and raise CA see above.
3. feeding corals causing shrimp to crawl all over corals and literrally snatch it from their mouths. This can go on for hours until every last particle of food is gone..
Sorry for the long post I'm kind of detail oriented.