Do most corals shrink

From 8 pm till 1 am are the moonlights..at 7 am to 9 am is early sunrise9-12 is high noon from 12-5 is the strongest and then at 5-8 is dusk which is blue and 6 magenta LEDs and then the moonlights from 8-1

 

If they have gotten into a pattern it could just be their natural reaction to their day to day cycle. Do you have any inverts like crabs or shrimp? I had a cleaner shrimp who spent each night after feeding doing laps around the aquarium touching every LPS he could, they would all shrink at night right before feeding. It was quite amazing.

 

I have 3 emerald crabs a blood shrimp a cleaner shrimp and a banded coral shrimp

 

It's wierd sometimes the crabs pick on the corals ,not all the time but every now and then thinking of getting rid of them

 

My Duncan does this from time to time. It's usually about 7:00pm. Could there be a change in ph during the shrinking?

 

Sounds like they are reacting to the night cycle that starts at 5... when the blues come out they go into night mode. Lots of changes happen after the lights start to dim. Especially out of LPS