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duration of lights for saltwater reef aquarium


aliyesami

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aliyesami

how many hours of light is recommended for salt water coral aquarium ? I read an article saying we should leave the lights on for 12 hours n then another article was talking about 8 hours.

is there any established rules for this ?

 

thanks

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10 is usually a good number to least start.

 

Longer can influence algae growth and acclimation of new corals is more difficult.

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So corals mostly run out of the metabolites to be able to continue growing after about 4 hours. So you need 4 hours per day at the very least but technically dont need much more than that (at least for corals, this probably doesnt apply to things like clams). Some coral growing facilities run two light cycles per day because of this fact. Some people run as low as 6. At the other extreme people simulate a full day on the tropics which is 12 hours. I would only go toward 12 hours if you have a pretty significant sunrise/sunset. Even then you may be encouraging some algae growth because after 4 hours, your corals arent soaking up much more in nutrients but your algae can grow allllll daaaaaay loooooong.

 

Personally I run 10 hours with a two hour sunrise/sunset on either end giving me 6 hours at full power. I may move that back up to 11 or 12 hours but I have yet to decide. Not really a correct answer here. Stick somewhere between 8 and 12 and essentially find what works for you in terms of viewing time, algae growth and coral health/growth.

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Nano sapiens

^^ I use the same schedule.

 

The lighting duration can also be dependent on the intensity of the lighting system. A higher powered system can stress corals if run too intensely for too long. Conversely, a lower powered system can be operated on full power for more hours (up to ~12) to somewhat compensate for the lack of intensity.

 

Look to the coral's reactions as a guide. for fine adjustments.

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NorthGaHillbilly

I run my actinics for 12 hours and the halide for 6 hours. my goal in the future is to build a hybrid lighting fixture to allow for LED actinics, LED full spectrum to ramp up and down for a dawn-dusk effect with the halide coming on for ~4-5 hours mid day

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Should the sunrise or "blues" in this case be kept to a minimum since the corals growth is prime within the first 4 hours?

 

Would four hours straight of low PAR moonlight stunt the growth of corals compared to blasting the whites right away?

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Should the sunrise or "blues" in this case be kept to a minimum since the corals growth is prime within the first 4 hours?

 

Would four hours straight of low PAR moonlight stunt the growth of corals compared to blasting the whites right away?

 

As far as I understand it, no. Basically, they use up the nutrients they need to grow in 4 hours of full sunlight (then replenish them overnight). Assuming, for the sake of this example, that it didnt kill them or stunt their growth because they got too little light, if they were getting say 1/2 of that energy then they would use up those metabolites in 8 hours instead of 4. Now this isnt really how it would work but you understand the point.

 

Plus, in the real world, corals go through dawn and dusk every single day out in the wild and I dont think their growth is stunted :D .

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Would running the lights during the spring and summer for longer, lets say 10 -12 hours and cutting back to around 6 - 8 hours during fall and winter have any positive effects for health and growth?

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As far as I understand it, no. Basically, they use up the nutrients they need to grow in 4 hours of full sunlight (then replenish them overnight). Assuming, for the sake of this example, that it didnt kill them or stunt their growth because they got too little light, if they were getting say 1/2 of that energy then they would use up those metabolites in 8 hours instead of 4. Now this isnt really how it would work but you understand the point.

 

Plus, in the real world, corals go through dawn and dusk every single day out in the wild and I dont think their growth is stunted :D .

In the wild sunrise lasts about 2 minutes at the equator, about 3 minutes in the states.

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Nano sapiens

Sunrise is quick, but one thing to consider is that sunlight doesn't start to penetrate the water's surface until ~15 degrees ('angle of incidence'). At typical reef depths harboring coral of 10-15 meters, violet and blue light predominate first (shortest wavelengths/most energetic), followed by longer wavelengths with the 'full spectrum' at around noon. In very shallow water,more of the light spectrum is available much sooner since light attenuation is much reduced.

 

As far as summer vs. winter day lengths, this depends on the latitude. On the equator, there isn't really much difference. However, the further north or south the reef is located (up to a maximum of around 30 degrees latitude), the more the seasonal light variance. For example, at 30% latitude (eg. Caribbean) the summer day length can be nearly 14 hours and winter slightly over 10 hours. Most coral reefs occur at or near the equator, so mimicking the 12 hr daylight all year would seem the most appropriate.

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Would running the lights during the spring and summer for longer, lets say 10 -12 hours and cutting back to around 6 - 8 hours during fall and winter have any positive effects for health and growth?

 

I wondered this as well. Example,some plants will grow (vegetative state) with longer photo-periods, but only fruit (reproduce) when the light time is cut back, a natural cue that winter is approaching. I realize that this is very general, but I could definitely see how this would have an impact, good or bad. Some corals seem to have their reproductive cycle tied to moon phases as well.

 

Most coral reefs occur at or near the equator, so mimicking the 12 hr daylight all year would seem the most appropriate.

Seems reasonable.

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In the wild sunrise lasts about 2 minutes at the equator, about 3 minutes in the states.

Good point, I hadnt thought about it. That said, the low light still lasts for a decent bit. Intensity builds pretty slowly. I actually did some research on the intensity at sea level (in PAR) for sunlight near the equator and originally mirrored my light schedule on that. I dont think i still have the articles on it but it basically amounted to a bit less than a 3 hour ramp on either end of the light cycle (on a 12 hour cycle). Of course that wasnt a perfect representation because I cant replicate neat mathematical curves, just straight ramps and that was about as close as I could get.

 

Would running the lights during the spring and summer for longer, lets say 10 -12 hours and cutting back to around 6 - 8 hours during fall and winter have any positive effects for health and growth?

I dont know if it would help corals much, other animals do respond to seasons more than corals seem to. I know that some fish who rely on seasons for breeding (at least most of the ones I used to breed) tend to respond more to temperature change than anything else, so we would up the temp by a degree or two to get them to start to breed and then bring it back down later. Dont know if any corals would respond this way though. Some people actually do the opposite just to combat the heat in the summer but thats just a practical thing.

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I remembered I included a graph from one of the articles I looked at when I talked about my light build. Its in this post, toward the bottom. This one was measured in Israel in the summer so its a hair longer than 12 hours and intensities would be different but that doesnt really matter too much for our purposes. The curves at the equator are very similar, but are right at 12 hours.

http://www.nano-reef.com/topic/301644-the-athenian-reef-7529-update-2314/?p=4595361

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