Acropora loosing colors: possible reasons?

[meermann]

Hi guys,
in the beginning of March I bought this stick of FM Dragon Breath. It encrusted the base, despite of slow growth.
Few days ago it had dark red colour with green tips. Now the colours are almost gone.
The tissue is still there, but it looks very pale.

Since the middle of May I've changed nothing (except 3 or 4 times I used GAC to remove yellowish water color - around 5tbs on my 40G tank)

NO3 is 5-10, PO4 is .08 - .11, Alk is 7.7. Recent ICP tests are also OK

The PAR on this stick was 320-340 since March. Yesterday I raised the light about 2"

I use no supplements, except All-For-Reef and fish food.

I inspected this acropora for pests - and haven't found any signs of AEFW or nudibranches.

I have neither polyp-nipping fishes nor crabs/shrimps/hermits. Only basslets, wrasses, tang and turbo snails (and a decorator sea urchin)

What could cause such discolouration and how to protect the acropora?

 

[meermann]

UPD: the tank is 14 months old, the temperature is 78, PH is 8.2-8.5 (I use a CO2 scrubber)

 

[sculpin01]

It looks healthy, although mildly pale. When in doubt (and everything else is in order), send an ICP.

 

[meermann]

It looks healthy, although mildly pale. When in doubt (and everything else is in order), send an ICP.

In the end of April the colours were more vibrant. The same place / light.
OK,I'll send the water to ICP.
Meanwhile if I add some Red Sea AB+ won't it make worse?

 

[sculpin01]

I wouldn't add anything until you get the ICP results. Paleness can be secondary to trace element excess, notably iodine.

 

[Pistondog]

Any windows nearby? Sunlight pales some of my across when it hits the tank thru skylights, this time of year.

 

[meermann]

Any windows nearby? Sunlight pales some of my across when it hits the tank thru skylights, this time of year.

There's a balcony in 10', but direct sunlight doesn't spread on the tank this time of year. In the middle of winter it does, but not in the summer.

 

[Dannyboy402]

My acros lost a little color when I bumped my light intensity up and when I have lower nutrients.

 

[ninjamyst]

Can mean anything. Pale or brown color means it is stressed / not happy. Can be too much light, not enough light, too much nutrients, not enough nutrients. Your parameters look fine so if it was me, I would try dosing aminos and keep a watch on nitrate / phosphate.