Light cycle, can somebody please explain??

[StevenSeas]

Ok so this may or may not be a total newb question but I am curious and want to know so I am going to ask anyways. The sunrise color temp is in the red spectrum around 3500k and rises to 6500K through the day and up to a peak of around 20000K and then back down to a redish color. So my question is why when marine aquarist have multiple light strips some with actinic (blue) and the others with a whiter light, do we set the timers so that the actinic lights come on first and then the white light join in later? Wouldn't it be more natural to start with the white light then add the actinic later to simulate the increasing color temperature? This is just a question of curiousity as I am planning out a diy LED fixture and have it mimic the day/night sunrise/sunset cycle, and thus would like to get it right. So is it better to start with actinic? even if I can slowly ramp up white LEDs then add the Royal Blue LEDs slowly? Please set me straight.

[justahobby]

Your stats are coming from under water are they? Water filters out light starting with short wave lengths first (reds). Most of our coral would benefit from 65K, it just looks ugly. If you can offset the yellowness w/ lots of actinic then you should be rockin a great look w/ great growth.

[StevenSeas]

ok so which should come first? and no they arent from underwater I forgot bout the water filtering out the light but even then it should still be a redder white rather than blue right?

[Europhyllia]

The sunrise color temp is in the red spectrum around 3500k and rises to 6500K through the day and up to a peak of around 20000K and then back down to a redish color.

Could you point us to your source for this? It was my understanding that 6500k is midday towards the water surface.

I never heard of it 'peaking to 20000k'. I would have expected the blue spectrum to be a matter of depth rather than light cycle (20000k indicating deeper waters).

I turn on the actinics first because they are not as bright as the white bulbs. If I used red spectrum lights instead of actinics I would use those I guess.
The consideration is that I would find it less startling to wake up to a less bright light source no matter what color it is.

[StevenSeas]

I dont have a source for the peak of 20000k i think i picked that up somewhere a while back while reading on Solaris or AI fixtures.

The consideration is that I would find it less startling to wake up to a less bright light source no matter what color it is. I guess this makes sense. but since I use HO T5 for both actinic and white and my "white" is at 6700K should that come on first?

[alton]

You are correct even though we don't follow those colors to wake up and go to sleep for our aquariums. We should start and end with red or warm colors not blue or actinic. To wake up in the morning I put 65K CFL lamps in my bathroom to quickly wake me up. (It is called a rude awakening)To go to sleep we should use colors in the 2500 to 3000 Kelvin range. To follow this you would have to add more lamps to your current setup. Have them come on first and go off after all others are on and then come on just before all others go off and then shut down an hour later to simulate sunset. I will see if I can find the power point that I received from IESNA a few months ago.

[justahobby]

Actinics are mainly for viewing pleasure and to extend your viewing hours. As Karin mentioned, it's probably easier on our fishes' eyes too.

[StevenSeas]

You are correct even though we don't follow those colors to wake up and go to sleep for our aquariums. We should start and end with red or warm colors not blue or actinic. To wake up in the morning I put 65K CFL lamps in my bathroom to quickly wake me up. (It is called a rude awakening)To go to sleep we should use colors in the 2500 to 3000 Kelvin range. To follow this you would have to add more lamps to your current setup. Have them come on first and go off after all others are on and then come on just before all others go off and then shut down an hour later to simulate sunset. I will see if I can find the power point that I received from IESNA a few months ago.
so if i were use 6500K LEDs and run them at 2% slowly up to 100% and then have the royal blues do this also and then back down would that be as close as I could get without adding red bulbs specifically for this application?

[justahobby]

^ You wouldn't be changing the temp... just the intensity.

[Mr Cob]

My only reason for using actinics is for extended viewing hours on the tank both front and end of the MH light cycle.

[Europhyllia]

I dont have a source for the peak of 20000k i think i picked that up somewhere a while back while reading on Solaris or AI fixtures.
I guess this makes sense. but since I use HO T5 for both actinic and white and my "white" is at 6700K should that come on first?

Your T5 lightbulbs in 6700 white probably have a PAR of about 300 while your actinic have a PAR of around 200 (+/-50). I'd still go with lower PAR over color accuracy for the wake up call :) .
However if you have LEDs and can bring them up gradually the by all means go with the 6700k if you want to immitate nature more closely
http://sites.google.com/site/tfivetesting/par

[txg8gxp]

Great thinking...Now I'm going to make it alittle more confusing for you.... Leds change kelvin output depending on mA. Like the xpg's(whites) range from 6500-8000. Just thought I would add alittle extra info.



so if i were use 6500K LEDs and run them at 2% slowly up to 100% and then have the royal blues do this also and then back down would that be as close as I could get without adding red bulbs specifically for this application?

[txg8gxp]

You are correct on the red light in the morning and evening, but Karin is right about the 20k. We never see 20k, but go diving and take a look.

[justahobby]

I assume that regardless of what the sun's temp is on land, the ocean is still filtering out the same red wave lengths. So if it's 3500 kelvin here, then the ocean still slows the waves down to 6.5, 10, 20
... and if it's 10k on land, then the water isn't filtering out as much, but the temp in the water is still the same. Only the intensity of light that isn't filtered is being changed. I am having a hard time finding stats one way or the other.

[Europhyllia]

Kelvin Rating, or simply K. Without getting too technical, is a numeric scale that describes the color of an object at a given temperature. For aquarium lighting purposes Kelvin rating describes the color, or spectrum, of sunlight in a given environment. Most aquarium light bulbs will have a Kelvin rating between 5000K-20,000K. For example, the approximate Rating of natural sunlight at sea level is 5500K, this is a very warm white light that includes all the colors of visible light(red,orange,yellow,green,indigo,violet) This is the ideal spectrum of light for shallow water aquarium plants and fish. The deeper you go into the water column the higher the Kelvin Rating becomes. 20,000K light bulbs are designed to mimic deep water environments. Red, yellow, and orange light are short wavelengths and get filtered out of the water column very quickly. Blue and green light can pentrate much deeper. The result is that the deeper you get in the ocean the more blue the environment becomes. Animals that live in these deeper water environments have adapted to the light spectrum at these depths.

[justahobby]

Thanks for posting that Karin. ^^ And that is where we get into 'our coral comes from all different depths w/ different requirements'...

[Europhyllia]

Thanks for posting that Karin. ^^ And that is where we get into 'our coral comes from all different depths w/ different requirements'...
Yes that's where the funny part comes in where the reef crest people with their high light requiring corals tend to be the ones that really LOVE 20000k bulbs. lol

[StevenSeas]

Ok i understand that i cant manipulate the spectrum being put out, well much, but starting at low intensity and then increasing would help ease them into 'hey its day time'. Then slowly throwing the blue in would raise the theoretical kelvin temp provided the light mixed. Right? Right now im not too worried bout looks i like a white light, but mostly want growth so i can make some big corals look great instead of some lil ugly frag plugs W/ some coral lol. Thanks for the info

[Salty]

...Red, yellow, and orange light are short wavelengths and get filtered out of the water column very quickly. Blue and green light can pentrate much deeper...

Actually, red end is longer wavelength than blue, just wanted to throw that out there. Not sure the source, but they should correct it on their site.

[Europhyllia]

Salty, you're right. But I think the rest of the info is correct. :)

[justahobby]

I think consisting time (timers) for daylight is more important than acclimating them everyday. Once their tissue has initially acclimated to the highest intensity it would take more than a night to change that. However their respiration process is on a timer so to speak which is why timers are a good idea. Oops I flubbed on red being short too.