STN or lack of light (or something else)?

[mdbronco]

Hi,

I've noticed the underside of my birdsnest bleaching out. Is this simply due to a potential lack of light or maybe something else? If it's STN then I guess I can refrag as needed, but what about lack of light? Is this just an inevitability as corals grow out?

Params are generally stable as far as my testing once per week can tell. I do weekly water changes of 10%

Calcium 400
Phosphate 0.25
Magnesium 1350
PH 8.0
Ammonia 0
Alk 10
Nitrate 5
Nitrite 0

AI Hydra 26s (2) and the piece is mid way. I've had it for about a year.

Thoughts?

 

[Charlie’s Frags]

That looks like lack of light in those areas to me

 

[Iván Olalla]

Very common in birdnest corals when lit by a more focused light, so yup lack of light

 

[JCOLE]

Hard to tell. Do the white areas have polyp extension that look translucent? If so, then yes, lack of light. If no PE and just skeleton then it is TN.

 

[JCOLE]

Here is mine from lack of light. Notice there is good PE but they are translucent. I am going to frag those this weekend so they can get some color.

 

[melanotaenia]

Birdnest are classic victim of the LED shadowing effect; there is no real "bouncing" of the light off surfaces with LED like T5/Halide, so large colonies will develop this over time.

Adding a supplemental T5 option should alleviate the problem. I have been thinking about this as well as my Acros start to grow out, currently running only LED, will most likely either add additional LED lighting to angle into the tank for better coverage, or use a T5/LED hybrid system.

 

[C. Eymann]

Totally agree with h2oh2o, look to see if its bleached , or if tissues is gone, to my eyes it looks like actual tissue loss from the inside of the colony out words which tells me tou should throw some more flow at it, this is actually very common with larger colonies of sertiopora.

 

[mdbronco]

Thank-you all! So I’ve heard both more light and flow. Light might be hard for me to add but flow I will tinker with. Flow for me is by far the most frustrating part of setting up this ecosystem...

 

[melanotaenia]

Even adding a little T5 supplementation will help, but I agree, it can be tricky because adding light can help, but you have to be mindful of how it may affect other organisms in the aquarium. I am not sure that more flow is going to help the situation, as this is a clear example of lower branches getting insufficient PAR to properly grow/color.