Natural Reef Photoperiod vs. Reef Tanks

[DBarsotti]

So I've been putting some thought into this lately.. I typically run my lighting for a13+ hours. This is mainly so i can feed my fish when i go to work and after work, i run my system at night to save on power.. It starts with the blue LEDs for half an hour.. Then the t-5's.. several hours later the metal halides kick on and run for 8 hours... Then they go off in reverse order.

What sort of photo period are you running?
On the natural reef the amount of light and the duration (around 14 hours) far exceed anything we come close to in our systems.

I've read people only running 8 hour photo periods, even 6, claiming this was more beneficial for the coral.. Wouldn't trying to replicate the natural photoperiod be the most favorable idea?
Where does this idea that less light is better for corals come from? how is this justified? I mean, what is the argument that a coral enjoys less light than what is provided in nature?

thoughts?

 

[am3gross]

Realalisticly we will never be able to match the sun at what it puts out, the cloudy days, the rainy days,so on and so on...I will argue that a six hour period is enough light if
It is the high intensity light... For example... I have 3 250 watt halides.. If one comes on at 12 and off at 6 then the middle comes on at 1 and off at 7 and then the last one coming on at 2 and off at 8... I am only running 6 hours however the corals are getting 6-8 hours worth of sunlight... Now I still run the supplemental lighting which is more for my viewing pleasure then anything else.. There are so many things in this hobby that are one persons idea and it is sworn to be the best way... I just go with what makes the coral or fish look good..if it is 6 hours then good for me and my electric bill. If its longer then it's longer... I will say that the last time I bought a coral it wasn't wearing a watch!!!! Lol

 

[Grant W]

I run a similar photoperiod to you.

 

[DBarsotti]

Not trying to be rude by any means, just seriously interested in the effects of lighting schedule.
I mean if a 6 hour period works and your corals have good color than I guess it really doesn't matter in that aspect.

What about growth? I'd be curious to see what sort of effects a shorter photoperiod has on growth. I would assume it has to have some, no?

 

[smsreefer]

Corals in the wild only really get about 4-5 hrs of truly high intensity overhead light everyday.
The early morning and later daylight times the sun is angled to the point that the intensity is no where close to the mid-day intensities.

I have noted the different intensities while diving in several far-south locations, and read a study or two which made me really take a look while diving the same areas at different times of the day.
I will see if I can locate the studies.

Now, I am not saying that in a home reef we are duplicating the sun intensities, but depending on the many variables on everyone's home reef lighting, a 6 hour high intensity photoperiod can work very well.
Once your corals photosynthesis saturation point is met, your lighting requirements have been met and they do not need or want any more high intensity light.

 

[DBarsotti]

I found this article. Not sure how creditable it is but it states that only a few hours after sunrise the light corals are exposed to is already way stronger than anything we supply in our tanks.

Check it out
http://www.fishchannel.com/saltwater-aquariums/aquarium-frontiers/natural-reef-light.aspx

 

[smsreefer]

Here is one good study on
photosynthetic saturation or when receiving too much light leading to harmful Photoinhibition.
http://www.advancedaquarist.com/2007/3/aafeature1

 

[DBarsotti]

Very interesting read.

From what I got from the article is that too much intense light can be harmful but it's not that the corals don't like full days of intense sunlight. They've just adapted to only use enough light to survive so they can handle not receiving 100% sunny days year round.

I agree that corals can do very well
In lower light or with shorter photoperiods. Just seems to me all the tanks I've seen with AMAZING sps growth and color are tanks that's are getting dumped on with light and for at least 8+ hours.

I really wish I had the funds to hook up two small tanks to my system with short and long photoperiods. Add several frags from various colonies and grow them out.

 

[karsseboom]

You do understand that the corals are not getting full lighting all day right? yeah 14 hours of total day light and about 7 hours of high intesive light. That is why people use t5 and MH to create a dusk to dawn effect. So when early in the morning the sun comes out at 7 the par is weak until about 2pm then the sun hits hard until about 7 or 8 then the par drops and the sun fades away. So in reality how much strong lighting are the corals in the wild getting? 14? no more like 7 to 8.

 

[Froggy]

I actually run a 14 HR photo period on my 120 T5 lit tank. I run an 8 x 54 watt Tek. Full lighting is 8 hrs and I have 4 bulbs running the rest of the photo period for dusk/dawn reduced lighting.

 

[DBarsotti]

You do understand that the corals are not getting full lighting all day right?

you did read where i said i run Led's and T-5's.. for several hours before my Halides come on and off. Right?



And as for Corals not receiving high amounts of light in the mornings and afternoons, That may be true with some corals, especially corals in deeper waters..

What about corals in extremely shallow water? some SPS are exposed to air and full blown sunlight during every low tide.

As seen here. These corals are definitely not struggling to adjusting to the plethora of light they're receiving, i would assume, throughout the entire day.

 

[drew11588]

i was watching planet earth when they showed something very interesting. they said that during the daytime corals obviously undergo photosynthesis to provide energy. however, the corals will grow and expand at night

 

[Alex T.]

Corals in the wild only really get about 4-5 hrs of truly high intensity overhead light everyday.
The early morning and later daylight times the sun is angled to the point that the intensity is no where close to the mid-day intensities.

I have noted the different intensities while diving in several far-south locations, and read a study or two which made me really take a look while diving the same areas at different times of the day.
I will see if I can locate the studies.

Now, I am not saying that in a home reef we are duplicating the sun intensities, but depending on the many variables on everyone's home reef lighting, a 6 hour high intensity photoperiod can work very well.
Once your corals photosynthesis saturation point is met, your lighting requirements have been met and they do not need or want any more high intensity light.

I would have to agree with this. No matter how we try to mimic sunrise and sunset, our tanks are actually only lit from above, and on average for a much more pronounced period. If you've ever snorkeled or dove a coral reef you would see the light in the morning hitting the corals on the eastern side from a much more shallow angle than we can provide in our footprints. It would be akin to lighting the tank in the morning from the side panel and slightly above. Then toward the afternoon blazing hours it's from above but only briefly. The light throughout the day is actually on an arc rather than linear like we provide. Sometimes corals in the wild will never really see an intense dawn or dusk lighting at all because of where on the reef wall they may be. While it's true that many SPS keepers that have incredible colors and growth run long photoperiods, I'm willing to bet that they didn't acclimate them that way.

SPS corals can and will handle a lot of light, but definitely need to be acclimated to these extended photoperiods. Frag farmers with light rails seem to get incredible growth and color. WHile they may have an 8 foot tank lit for 8 hours a day at shallow depth with 400 watt bulbs, it's actually going to be only about a third of that for every 2 feet while a single bulb on a light rail passes over throughout the day...much closer to what the sun and clouds may do in the wild. Just an observation...no science behind it whatsoever. With 400 watt Radiums I had my best growth with a 5 hour halide photoperiod and 10 hour actinics.

 

[karsseboom]

Yes this was point, the early noting sun is not strong and corals are not receiving high intensity par. There olny really getting full sun for about 6 hours.

 

[DBarsotti]

I'm just going to have to man up and do a test. Ha

2 tanks.. Several different species of sps, at least 2 frags of each specie in each tank. One 12 hour photo period and one 6 hour? No morning/evening lighting just one Light intensity for those durations.. Take pictures every few weeks. Sounds pretty fun to me.

I of course need to get my new display up first (priority) but I will seriously start looking into doing this.


Side note* I completely agree that corals have to be acclimated to extremely strong lights and also longer photo periods. That's a no brainer, I've fried my fair share of frags. Ha

 

[allsps40]

I also agree that corals in the wild only get about 6-8 hours max of full intensity PAR sunlight. The dawn and dusk sunlight is much weaker and the suns rays are angled more so light does not penetrate as well, even in shallow water.

 

[MammothReefer]

Ha.. I'm just going to cut and paste what I put on the other forum, same discussion, same people, 2 locations..

I run my DT for around 6 hours, and my frag tank for 4. Seems to work for me, good steady growth and my colour can be good depending on other factors.

hmm or should I have taken opposing point of views!

 

[klepto]

Dom, check out this article: http://www.coralscience.org/main/articles/aquaculture-a-husbandry-4/insights-high-irradiance

I think it addresses your exact question pretty well.

 

[MammothReefer]

you did read where i said i run Led's and T-5's.. for several hours before my Halides come on and off. Right?



And as for Corals not receiving high amounts of light in the mornings and afternoons, That may be true with some corals, especially corals in deeper waters..

What about corals in extremely shallow water? some SPS are exposed to air and full blown sunlight during every low tide.

As seen here. These corals are definitely not struggling to adjusting to the plethora of light they're receiving, i would assume, throughout the entire day.

Who's to say though, maybe that is a 100 years old and took that long to grow. Maybe if it was 10' under water it would grow twice as fast. We don't know circumstances around how long it took for that coral to get to that point, or if it's healthier, or less healthy then say the same species 10' over and under. Or maybe it' the opposite maybe those corals on the surface grow twice as fast as those exposed to light 10' under..

 

[karsseboom]

Who's to say though, maybe that is a 100 years old and took that long to grow. Maybe if it was 10' under water it would grow twice as fast. We don't know circumstances around how long it took for that coral to get to that point, or if it's healthier, or less healthy then say the same species 10' over and under. Or maybe it' the opposite maybe those corals on the surface grow twice as fast as those exposed to light 10' under..

It looks pretty cloudy to me...