Acropora yongei that is darkening

[amarti2038]

Hello everyone

I have a coral, I think it is an Acropora yongei that is darkening on the side where it does not get light.

The parameters I have them quite stable in:

• PH: > 8 day and night
• PO4:0.02ppm
• NO3: 7
• KH: 8
• CA: 506
• MG: 1400
• 250L Mixed Reef

I dose RS AB+ and TM AFR+Kalkwasser at night with a Versa.

The aquarium is 11 months old, and this acropora is about 5 months old, of which 3 months it looked great (PO4 was high then 0.15 on average), it has grown well, had the polyps well extended, etc. For some time now it has been declining, closing more polyps and the bottom of the coral, which is in the shade, has begun to blacken as you can see in the photos. I think it's just lack of PAR, it's position has 220 more or less and I think it's too little, but my leds are already at 100%. 2x RS LED 90.

I have several questions:
- What is the black spot? Necrosis?
- Why does it appear? Lack of light in the shadow part?
- What is the solution? I have bought some new, more powerful LEDs, the Noopsyche NP K7 Pro V3 but they have not arrived, even so, I don't think they will improve the shadows.
- How do you mitigate the shadows problem?

Thanks and good Sunday afternoon!

 

[KrisReef]

I’m hope I’m wrong but is that an AEFW in the 1st photo on the far right underside of the branch?

They do tend to hide underneath and out of sight when present. My phone and weak eyes are having trouble confirming what I’m looking at.

Shaded branches often look different but they don’t look like they have an open sore like this one
.

 

[amarti2038]

Oh, it could be yes, I post another photo with more light in the dark part to see if we can confirm it. In that case how do I treat the coral? RS DipX? Thanks!

 

[KrisReef]

The second picture doesn’t show any AEFW which is good news. Not certain why the anacropora is loosing flesh in the shaded areas?

 

[SamMule]

That coral looks very pale IMO. I bet you're stripping too much phosphate from your tank. PO4 of .15 is nothing to worry about, but .02 is very close to 0 and well within the testing error range of our test kits. Did it start getting pale after you lowered PO4?
I would suggest reducing whatever method you're using to remove phosphate from the system.

 

[amarti2038]

That coral looks very pale IMO. I bet you're stripping too much phosphate from your tank. PO4 of .15 is nothing to worry about, but .02 is very close to 0 and well within the testing error range of our test kits. Did it start getting pale after you lowered PO4?
I would suggest reducing whatever method you're using to remove phosphate from the system.

The Phosphat its fine now, I use the Hanna Phosphorus 736 wich measures in PPB and has a lineal relation to Phosphates of 3.066. I didn't apply the 3x value and I had high PO4 because of that. I was dosing PO4 to upper it. I installed a Trident NP and after that I realised I had the 3x issue with the hanna. I did a water change and lowered the po4 value like that. But its fine, not? 0.03ppm its the recommended po4 value. The change on po4 may have affect but I think its a low PAR issue, as the acropora receives 220 PAR and a green slimmer should receive more, not?

 

[Dburr1014]

The coral is bleached and the shaded areas are dying.
After the flesh dies off, other things attach to the bone structure and it turns dark.

I see you bought new lights but not here yet. Do you know par currently?

Your po4 was 0.15 and now 0.02 or higher. @SamMule is referring to yous and downs of po4. Acros don't like that number swinging willy nilly. Try to keep it from going down rapidly. I recommend 0.05 to 0.15 as a good number.

 

[PapaFishRocks]

New acronym for me.
What is AEFW?

 

[xabo]

https://www.reef2reef.com/threads/guide-to-common-hitchhikers-in-reef-tanks.909223/
Scroll down you'll find it.

 

[Dburr1014]

New acronym for me.
What is AEFW?

Acropora Eating Flat Worms.

 

[amarti2038]

In the end I bathed the coral with Rs DipX just in case of AEFW. Then I made a small frag in case the main one doesn't pull through and repositioned the coral as high as possible on top of my rocks, it has gone up about 5 inches, on its new position should increase a bit the PAR 260+-. The frag was positioned on one side of the aquarium almost touching the surface. The new lighting comes from China and has not yet arrived. Let's see how it goes. Thanks guys!