LEDs and shading; is it BS?

[madweazl]

I've seen a number of posts on various forums regarding LEDs and the shading issues they create that lead to STN at the base of corals. The notion seems crazy to me because many of my SPS grow in areas of almost no light without demonstrating this behavior. It seems to me there has to be something else that causes this or is exacerbated by the lack of light instead of purely a lighting issue. One of the videos by Triton showed corals that were growing well on the undersides, out of light as well.

 

The frags in the picture below are only three to four inches in size but have extremely heavy shading; the one of the left is illuminated by a Kessil mounted to the right of it, so there is heavy shadowing cast to the left of the coral; it actually has more growth in this area than anywhere else. The one on the right grew down and behind a ledge that protrudes roughly 3/4" outward (toward the viewer). I have a pikachu that has grown well into a crevice/cave in the rock that couldn't receive less light unless there were none.

 

Any theories on the root cause? Am I crazy? These are just frags, you dont know what you're talking about? Any other thoughts? 

 

 

Edit: The only adjustments made to this image were exposure, white balance, and lens correction; no contrast, no saturation, nothing else.

 

One thing I will add is that I don't use filter socks and I feed heavy (LRS Reef and Herbivore Frenzy; typically one in the morning and the other in the evening). I add nothing else to the tank (i.e. phyto, reef roids, etc.). You can see there is quite a bit of stuff suspended in the water column in the image I posted. Does that make the/a difference?

Edited December 30, 2017 by madweazl

[mari.harutunian]

I use two original AI hydras and i have recessing flesh on certain acros and major polyp extension on others in shaded areas. The upset one is a stag horn. The ones that do well are birds nests- possibly excluding seriatopora I’ll have to check when i get back.

 

 

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[gmerek2]

the technology is getting better I think a lot of the LEDs have a wide angle allowing reflection off glass. It prevents the spotlight effect. Knowledge of the problem is getting better most vendors and companies suggest multiple fixtures even with smaller tanks. Better spread = more angles to get where the sun don’t shine. Now with that being said I have seen some bad shadowing. Typically it’s a tank that has only one LED fixture. And the fixture typically doesn’t have a lot of spread.

[madweazl]

Was just scrubbing the algae off the back of the tank and noticed a response from a few of the corals. The image is purposely over exposed (I'm no Photoshop guru, sorry) so you can see the polyps in the shaded areas better but they sure did open up to grab hold of whatever may be coming their way. 

 

 

I mentioned LED but I don't think it matters, shade is shade, right?