Corals turning brown?

[alvinhsu]

I have a 28g JBJ , lit with a 20k, 150 watt HQI. 9 hours of light per day.

I have a few Acan and a pinkbirds nest. The corals are doing pretty well, acan are developing new heads, the birds nest is growing and branching, I don't understand why the pink birds nest is now a brown birds nest, and the brightly coloured acan are now kind of brown. It is definately not nuisance algae growing on them. NOw is it possible that my lighting schedule may be too aggresive, and that the brown is actually being cause by a bloom of zooxanthelle with in the corals?

 

[ZANYMASTER]

Check your PO4.

 

[akma]

9hrs are too long I think. I would cut the halides down to about 6hrs.
What are your tank parameters.

 

[Master Shake]

is there enough flow on the birds nest? How high is it in the tank? at the top i hope. What are your phosphates and nitrates? What is between the actual light and the coral and how high is the light off the tank?

 

[KuyaMark]

check your po4.

+1

 

[alvinhsu]

-Parameters 0-0-10, PO4 is 0.4
- I have lot of macro in the tank to filter.. a fuge with mangroves and chaeto, some gracilera
- skimmer is a tunze 9002
- birds nest is place top third of tank, moderate to high flow, acans are in the sand bed.

any other thought out there?

 

[KuyaMark]

what are u using to test for phosphates if u dont mind me asking?

 

[alvinhsu]

Potassium pyrosulfate

 

[FaviaFreak]

Try cutting your photoperiod back to 5-6 hrs