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Discussion Starter · #1 ·
Looking for some information. Are actinic lights the same as moon lights? Or can they be used as them by dimming down LEDs? Or are moon lights completely different? Any information is greatly appreciated.


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'Actinic' is a common industry / hobby reference to extreme blue light used over reef tanks. It's most common reference is to fluorescent based 420nm, which is dim violet to our eyes but causes soft corals to radiate the color back in various bright colors. Once the wavelength gets much shorter, around 400nm and less, then you're talking UV-A. Conflicting evidence as to such wavelengths having any growth benefit, so actinic is typically used for aethestic reasons. Halides typically throw some sporadic actinic light along with some UV-A, but it's highly variable among bulb types given it's not the prime emission the lights are designed for. Reefers usually augment halides with 420nm Actnic tubes *if* they want extra color.

Common LED lights have little energy below 445nm, and while a few oddball fixtures (or DIY rigs) incorporate some 400 or 420nm LEDs it's the exception and not the norm. Unlike the more beneficial 450-460nm growth band emitted by white and royal LEDs along with reef halides LEDs are very inefficient at producing Actinic or UV light. So, I'm seeing a trend for the industry to blur the definition of 'Actinic' to include blue only LEDs often sold as 'Actinic strips' even though these LEDs are just vanilla royal blue as far as LEDs go . By definition they are not 'Actinic' in the classic sense as 420nm tubes, but the original term was never quite official in the first place :)

Many popular LED drivers are not capable of being dimmed 100%, but only go down to 20% or so. This makes them too bright at the lowest setting, so 'moonlights' often refer to a single LED, or a group of low power LEDs that are just bright enough with the other lights off to provide a couple lumens of light in the tank. Aka, 'moonlight'. However, depending on the driver in the fixture some are capable of full 100% dimming and with the right controllers the main LED light can do double duty as a moonlight. If the driver or LED fixture is capable of 100% it will usually state so.
 

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Discussion Starter · #3 ·
Wow! That was a great response. Thanks for taking the time. I do have a DIY LED set where each 18" heat sink has 24 CRE Royal Blue LEDs, 6 CRE blue LEDs and 15 CRE cool white LEDs. I have three different setups like this all the same (18" heat sinks with 45 LEDs each). If I am reading your post right then assuming the driver on the cool white lights could be dimmed down enough then these could be my moon lights. Or would it be more beneficial to use the blues as the moon lights assuming they could be dimmed down? Thanks again for your time and information.
 

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'Actinic' is a common industry / hobby reference to extreme blue light used over reef tanks. It's most common reference is to fluorescent based 420nm, which is dim violet to our eyes but causes soft corals to radiate the color back in various bright colors. Once the wavelength gets much shorter, around 400nm and less, then you're talking UV-A. Conflicting evidence as to such wavelengths having any growth benefit, so actinic is typically used for aethestic reasons. Halides typically throw some sporadic actinic light along with some UV-A, but it's highly variable among bulb types given it's not the prime emission the lights are designed for. Reefers usually augment halides with 420nm Actnic tubes *if* they want extra color.

Common LED lights have little energy below 445nm, and while a few oddball fixtures (or DIY rigs) incorporate some 400 or 420nm LEDs it's the exception and not the norm. Unlike the more beneficial 450-460nm growth band emitted by white and royal LEDs along with reef halides LEDs are very inefficient at producing Actinic or UV light. So, I'm seeing a trend for the industry to blur the definition of 'Actinic' to include blue only LEDs often sold as 'Actinic strips' even though these LEDs are just vanilla royal blue as far as LEDs go . By definition they are not 'Actinic' in the classic sense as 420nm tubes, but the original term was never quite official in the first place :)

Many popular LED drivers are not capable of being dimmed 100%, but only go down to 20% or so. This makes them too bright at the lowest setting, so 'moonlights' often refer to a single LED, or a group of low power LEDs that are just bright enough with the other lights off to provide a couple lumens of light in the tank. Aka, 'moonlight'. However, depending on the driver in the fixture some are capable of full 100% dimming and with the right controllers the main LED light can do double duty as a moonlight. If the driver or LED fixture is capable of 100% it will usually state so.
Information is really helpful. I was looking for real facts about LED lights. Thanks again.
 

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Wow! That was a great response. Thanks for taking the time. I do have a DIY LED set where each 18" heat sink has 24 CRE Royal Blue LEDs, 6 CRE blue LEDs and 15 CRE cool white LEDs. I have three different setups like this all the same (18" heat sinks with 45 LEDs each). If I am reading your post right then assuming the driver on the cool white lights could be dimmed down enough then these could be my moon lights. Or would it be more beneficial to use the blues as the moon lights assuming they could be dimmed down? Thanks again for your time and information.
I use blue led lights for my moon lights, didn't care much for white moon lights. I think that is going to be something you will have to try and see what your taste is.
 

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The new to me(thanx Paul) current outer orbit hqi/t5 fixture has both blue and white moon lights. They are very pleasant when both are on.
 
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