What Does It Mean ?

I keep the light on my reef tank for 12 hours/day. Many of my corals close up a couple of hours before that. Are they telling me they have had enough light for the day ?

 

I have always thought this due to their inherent nature. In their natural habitat the sun, of course, rises and sets at certain times year round. My lights start to go off (mine go off in three phases) at 7:00 pm but around 6:30 pm some start to withdraw and/or close. They seem to sense when things are winding down.

 

So, do stick with a certain amount of hours a day or do you watch your coral ? Mine to not start closing @ the same time everyday.

 

Which corals are closing ?

Mushrooms, LPS, sps should be staying open the entire lighting period. It it is one or two that seems within reason but all no. IME the corals are not even fully open until 3 -4 hours into the photoperiod.

And 12 hours is kinda of long, personally I shoot for 8 hours. Corals can get too much light. They start to accumulate O2 within their tissues and this can cause problems. In the wild lighting is not constant, wave action, clouds all allow some rest from photosynthesis and I believe that is important to some degree.

 

IDK mine stay open until I turn the light off, then when I turn the moon light on they open up again.

 

I run the main lights for about 8hrs a day. It takes my corals about an hour to fully open after the lights come on and then about 30min before the lights go out, some start to close up a bit. I think it's partially due to a habitual nature, they get used to a certain amount of light for a certain amount of time and then "know" when the lights are about to go out.

 

Yes, stick with a certain amount of hour. 8 hours of all light and 1-2 hours of actinic can be tacked on the front and back of the 8 hour cycle to simulate dawn/dusk. Some coral will close at different times because they have gathered in nutrients and particulates and close to feed.

 

Thanks so much. I'll go with the 8 hours & one hour of dusk on each side. It my frog spawn & Kenya tree frag that close up before the 12 hours are up.
Again, thanks for the advice. Where I live, it is 4PM. The bright lights have been on since 7AM. That is already 9 hours. Just just turned on the dusk lights & will leave them on for a couple of hours. Tomorrow, I'll try it your way & see what happens.Thanks again. I hope it works.

Gary.