Lobophyllia Hemprichii light sensitivity

[spaulr]

I picked up a crazy neon red branching Lobophyllia Hemprichii a few weeks ago. Currently it sits under a 150w 10k metal halide and 2 39w t5's (actinic+ and true actinic). When the halide turns off at night, the coral immediately recedes like it was shot by something. Granted, it comes back out eventually - the T5s stay on for another 1.5 hours. Still, is this behavior caused by the zoanthelle in the coral, or is it just shock from the light stopping? Anyone else seen or experienced this with their corals?

Coral otherwise seems very happy - all shipping nicks have grown back great.

 

[Len]

I've never had my Lobo behave like this. I find it behaves like most other LPS and is slow to react to stimuli. Is this the only LPS in your tank that behaves like this? I wonder if there isn't a little stray electricity leaking into your tank when the halides are powered up and down. Changes in light levels usually doesn't induce this type of quick reaction IME

 

[spaulr]

The only other LPS coral I have in the tank is a small candy cane. It seems pretty happy all the time and have not seen this behavior with it. Only when a hermit crawls over it. I can't imagine any current leaks, but I will double check the cord situation. I only have 1 heater, 2 nano streams, and 2 mag 7s (skimmer and return from sump) in the water, all with only 5 weeks of operation on them. Lights are on a separate circuit too.