Acropora change color

[naacs]

Anyone can tell me why my Acropora corals lose the colors that they have and change to brown colors.

The setup of my aquarium is:

115cm x 45 x 50

and have:

4 x T5 lamps - 2 blue 54w + 2 daylight 54w
4 x T5 Lamps - 2 blue 39w + 2 daylight 39w

In my other aquarium the setup is the some size but the light is:

2 x HQI 150w + 2 x T8 40w blue

The parameters of the water are good (i think):

Ph - 8.3
Kh - 8 - 9
Nitrate: 0
Nitrit: 0
Calcium: 400mg/l

Temperature: 25ºC
Salinity: 1024

Anyone have an answer to this problem?

 

[Creetin]

I would suspect its elevated po4.
You probably would get better responces in the sps forum.

 

[XxMutedYouthxX]

what are your phosphates at? normally acros brown out due to not enought light or too much phosphates

 

[JenDub]

try asking here:
http://reefcentral.com/forums/forumdisplay.php?s=&forumid=73

These sps guys are excellent at getting back quickly.