What's the low-down on reef moonlighting?

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Fungus

Aquarium Advice Regular
Joined
Jan 1, 2011
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Location
Los Angeles
I'm trying to understand what the purpose is for moonlight in a reef aquarium. Is it functional to the livestock, or simply aesthetic? I've heard two perspectives:

1. So-called "moonlight" is a low-power light of a color that is imperceptible by livestock in the tank. The purpose is to allow the hobbyist to observe nocturnal activity in the tank without disturbing the fish, etc.

My response: Shouldn't we use red lighting to avoid disturbing livestock? Moonlighting is usually blue, right?

2. Moonlight brings out some fluorescence in hermatypic life, like corals. It further mimics a natural light cycle in the tank and stimulates more coral growth, marine breeding behavior, etc.

My response: If you stimulate coral overnight with moonlights, do they ever get time to rest and repair?

Thus, I'm left with the following unanswered questions. Would love to know what you experienced reefers have to say.:confused:
* I read that moonlight fixtures are around 455-475 nm. Why is the light blue if moonlight is reflected sunlight? Aquarium Lighting Selection Guide: Which Aquarium Lighting System is Right for You?
* How many watts of moonlight is appropriate for a given size of tank? Is it essentially weak actinic lighting?
* Does the addition of a lunar photoperiod affect the behavior of tank inhabitants?
 
You can use red light if you want but the "moonlight" won't bother anyone since it is so low of a light. The bioluminescence is coming from the symbiotic bacteria living within the coral so I don't think they are being disturbed. I'm not sure what range nm that the lights run so I can't help you there, sorry.

Sent from my X10a using Aquarium
 
About the lunar photoperiod: it can affect fish behavior. I learned in my fisheries class that a lot of marine fishes time their spawnings to coincide with other species of fish so that there is soooo much fry, in the next few days, that it gives everyone a better survival chance. I'm sure other factors influence this spawning behavior but I know lunar cycles are one of them. I don't know about other behaviors though

Sent from my X10a using Aquarium
 
So what is the difference between actinic light and lunar light? Both are around the same wavelength of blue. Is it simply a matter of brightness?
 
For any color moonlight it is a matter of brightness. My LED lights go from 0 illumination at New Moon to 10% at Full Moon.

Think about how bright a full moon is in the open ocean around the equator.
 
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