acropora yongei is losing his tissue

[manuelink]

hello i got my sps acropora yongei for almost 10 months
and when i brought was growing very well
but since 3 months it was losing his tissue slowly
do you think that is a problem of lighting? or problems with parameters of water?

thank you

 

[manuelink]

ok nitrate 10ppm
ph 8.3
dkh 7
ca 440ppm
po4: 0

lights: 4/65w actinics
1/400w radium

45gal total

 

[velvetelvis]

I'm a noob when it comes to SPS myself, but I'll give you a bump by asking a question: what kind of powerheads are you using? SPS corals tend to like a lot of current, from what I understand.

 

[njfish77]

nitrates are a little high. dkh is fine at 7 but i would bump it to 8 so i doesnt stray into the 6's. You also have a 400w halide on there, where is the frag positioned? are you acclimating it to the light?

 

[njfish77]

sorry youve head it for 3 months didnt see that. Could be flow. What are you testing p04 with?