Lighting Schedule

[Jeremy Lain]

Hello,

Is this lighting schedule alright for a reef tank?

On 8:00 AM - 10:30 AM and 6:00 PM - 1:00 AM for a total of 9 1/2 hours?

 

[mta_morrow]

All if you living inhabitants will need a light cycle like a normal day. Meaning 6-8 hrs of appropriate lighting cycle.

However you can shift that entire cycle to accommodate you viewing time.

My lights come on at noon, ramp up for 2 hrs to peak, 6 hrs at peak, 2 hr ramp down 8-10pm.

 

[Crabs McJones]

I dont know that I'd do a short photoperiod, off and then a long photo period. What I would do instead is just have your lights come on later in the day. You could do a 10 hour light cycle from 3pm to 1am. I have my lights run from 11am to 9pm

 

[Ron Reefman]

Jeremy, I don't think the 2 1/2 hour morning cycle is good for the tank. But that's just my opinion, no good science behind it but a credible scientific concern.

Corals are the ones who really NEED the light. Most corals need a good, strong, midday type light for 5 to 8 hours. It takes the zooxanthellae in the coral about an hour to get the chemistry of photosynthesis started inside the coral polyps. Then it will do 4 to 6 hours of photosynthesis and shut down. Having light for a longer time period will not allow for more photosynthesis. The ability is genetic and evolved over millions of years of being in tropical water with good strong (overhead sun) for 6 to 8 hours. It will not change just because the light is on longer. However, having the light on longer doesn't do any damage as long as the coral gets a daily night cycle. And longer photo period may allow for more pigment production.

I'd be concerned that the 2 1/2 hour morning cycle could cause issues with the zooxanthellae doing photosynthesis. It would get started and just as it's going along the lights go out way too soon. Does that have any effect on how well, or even if, the zooxanthellae can start up doing photosynthesis again in the evening. It is getting a good 8 1/2 hour rest period, so it may be perfectly OK. I just don't know.

I'd suggest getting a light fixture that can be dimmed so the morning cycle isn't even strong enough to get the photosynthesis cycle started. Think about the 12 hours plus that the sun is up in the tropics. But only from about 8 or 9am to 3 or 4pm is the sun overhead and bright enough in the water for photosynthesis to work. At dawn and dusk the sun is at such a steep angle that the light doesn't penetrate the water enough for photosynthesis. So do a dim morning lighting that may not confuse the zooxanthellae into starting a photosynthesis cycle.

BTW, I do a very slow 5 hour sunrise, 4 hours of stable midday light and then a very slow 6 hour sunset. The last hour or two of sunrise and the first hour or two of sunset are still very intense and I estimate I get 8 to 10 hours of light intense enough for photosynthesis. But my most favorite times to look at the tank are early morning and late evening when the light is very blue and the corals and anemones fluoresce like crazy!

 

[jda]

I have never seen nor heard of a split cycle being any good. There were some AA articles back in the day that opined that it could possibly be OK, but nearly everybody that tried it ended up with regression in their tanks. The coral need nearly has much down time to regroup and gas exchange as they had when they were converting light energy - the quick cycle did not work out too well.

I would pick a viewing time and ramp slowly so that you can get keep it there. I run 10 hours with my Metal Halides on/off with strong lighting. A 12 hour cycle with some ramping is totally fine. Mine come on at 2:00 and go off at 11:00 since this when I am home to view. I run my frag tank for 11:00 since I do see more growth. I mostly only keep acropora and clams, so YMMV with other types of coral.

Some of this depends on what you keep. The shallower water stuff (think lagoons or acropora that is sometimes at the surface or out of the water) will get massive amounts of light as soon as the sun is visible, but the deeper stuff has to wait until midday to get a lot of light. This is one of those subjects where "everybody is right" depending on which coral is in your mind when you are typing. It has pretty well been shown that some of the lagoon 'nems and Tridacna want and can handle all the light that you can give them in an adaptation to always having high light.

 

[jtl]

I run mine for 12 hours including a 2 hour ramp up and a 2 hour ramp down. I run blues and whites in the morning and all blues in the afternoon. I am sort of following the WWC large tank schedule, I only wish mine looked like theirs.