Loss of color - Favia - grateful for any advice

[dppitone]

I would be grateful for any advice on why this Favia is becoming White on the edges-Thanks . . . Dave

-The type of coral - use scientfic names if possible.
favia

- How long you have had the coral
10 days

- How long it has been having problems
last 4 days

- The rate at which the problem is occurring/spreading
a little each day

- Any changes to the tank - equipment, additives, new livestock, etc.
no

- How long the tank has been set up
2 years

- size of the tank ( gallons or liters)
150 gallons, integrated with 1,000 gallon system

- nearby corals
zoa about 3 inches away. nothing else is close as its on its own ledge of live rock jutting out towards the front of the tank

Water quality:
- pH - 8.2
- temperature - 75
- salinity - 25
- nitrate - 0

Tank information I care about :
Lighting - (2) 400w mh 20k on outside, (1) 400w 10k in middle
Water flow - water flow, 20x turnover per hour
Placement - 18 inches from water surface, 5 inches above sand bed

-The outside ring of each polyp is turning white, while polyp center remain red. The rings were originally dark red.

http://reefcentral.com/gallery/data/500/79520favia.JPG

[DJ88©]

[moved]

[stevedola]

Id try moving it down towards the sand. THe 400w might be too much for this favia. Is the coral in direct flow?

[dppitone]

It's not in direct flow. I just moved it down and will see how if fares.

[David Grigor]

Move it down and can probably put it in indirect light as well if using 400w.....

[dppitone]

I moved it into another tank and its about 20" away from a 175w 14k bulb. So I'll see if that helps more.