HELP HELP Acro bleaching

[retin78]

I need help. One of my acro is bleaching at the tip. 2 days ago it was 3 tip and now a total of 5 tip of bleaching. water para
135 gallon tank total light output 750watts 3x250 hamilton.

sali---------.026
calcium----440
ph----------8.2
alk----------7.8
Nitrate-----0
amn--------.5 How do I lower that to zero? is been at that stage for over a year now.
magnes----1280. I think can't remember.

What do you guys think I should do?

[kravi]

I assume salinity is 1.026, not 0.026 :)

How much live rock do you have in the tank? And what are hamiltons? MHs? T5s?

How high up is the coral? Is the light too strong or to weak?

What is the temperature of the tank, and how much does it fluctuate during the day?

--Me

[retin78]

I have a chiller running so when the temp reach 80 degree the chiller will bring it back down to 78 and stop there. And it will raise again I don't know how long.

I'm using hamiltons MHs 3 of them

and the coral is about 4-6 inches below water level. Well the metal halides bulb are brand new. Just got 3 of them replace for about 1 week now.