Polyp die off of SPS

[Treefer32]

I have a large SPS coral close to 8" in diameter (maybe larger) about midway down my tank. And I noticed the bases of the coral bleached. I just thought it was lack of lighting and flow around the base. The tops of the coral continued to grow new branches and polyps are always out. However, recently I felt like the bases were getting more bleeched and the tops having less polyps. I noticed one branch almost in the center of the coral bleeched.

Yesterday I caught my Lamerack's angelfish biting at the base of the coral. I don't know if it's eating algae growing on the base or if it's actually eating polyps. I have other corals like this and they're continuing to grow just fine. The first image is the top with the bleached almost center of the coral. The other twoare of the bases of the coral? Thoughts? Or a dip may be necessary?

Other corals of similar type (just different color and smaller and a birds nest that's grown rapidly)

 

[Ron Reefman]

On a dense branching sps like a birdsnest coral, lower areas always die off. This is especially true if you have led lighting as it is more directional straight down than t5 or MH lighting.

 

[Treefer32]

Perfect this is what I suspect. So, why would one top in the middle of the coral bleech and the rest of the coral looks ok. Incidently it is the tallest of the branch. Too much LED lighting. I did recently change my AI Hydra 52s to be a longer lighting schedule and slightly different spectrum, with a longer time period at 100%... Maybe that one branch got too much light.