# Light Intensity & Temperature Changes Over the Day



## pipelayer (Sep 24, 2013)

Hello All,

I am wondering what color temperatures are used to mimic sunrise and sunset. 

All I have been able to find is that sunrise tends to be a little lower, maybe 5500K? While full sunlight is around 6700K. 

Anyone have any experience manually inputting color varying color temps throughout the day? 

Also, how long do you typically ramp up and down to and from full light intensity? Will an hour suffice? Should it be longer or does it not really matter? 

Surprisingly, I have not been able to find a lot of information on these topics. 

Cheers!


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## jeffkrol (Jun 5, 2013)

pipelayer said:


> Hello All,
> 
> I am wondering what color temperatures are used to mimic sunrise and sunset.
> 
> ...












Definitions are "inconsistent"..










As to "timing" really your choice...


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## pipelayer (Sep 24, 2013)

My understanding was that the top type of chart is based on film or phtography where that industry has standardized daylight to be 5000 - 5500K. 

The bottom chart shows 6500K which comes from a simulation of western europe (D65) but tends to be the standard in the aquarium hobby for mid day sun but I could be very wrong.

That being said, do you vary your light temp. throughout the day?


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## jeffkrol (Jun 5, 2013)

pipelayer said:


> My understanding was that the top type of chart is based on film or phtography where that industry has standardized daylight to be 5000 - 5500K.
> 
> The bottom chart shows 6500K which comes from a simulation of western europe (D65) but tends to be the standard in the aquarium hobby for mid day sun but I could be very wrong.
> 
> That being said, do you vary your light temp. throughout the day?


I do.... but I start (and end) at 660nm... 

Rough estimate..i've changed diodes and trimmed since..
https://youtu.be/VruO2w1d3Ls


Yes "daylight" is somewhat defined by "standard" d65 d50 ect...or by convention..



> Daylight in motion picture film world is 5600/5500 degrees kelvin. We (film industry peoples) made it the standard because some guy in some point in history determined that is what the average daylight color temperature is... although that number is not accurate most of the time, the standardization is important as it allows all daylight lighting in film/tv to be close to 5600 so our lights match other lights and daylight balanced film stock... and viceversa.
> 
> But in the real world, the light outside can vary tremendously based on weather, time of day, geological location, etc. That is why whomever came up with the daylight standardization may not match what actual daylight is in other parts of the world or in different weather.
> 
> Daylight can vary by thousands of degrees kelvin. Thus, lighting manufacturers who manufacture or incorporate non-tv/film bulbs into their products which are not specifically made for tv/film can pick whichever color temperature in the appropriate daylight spectrum they determine as daylight... in this case the bulb manufacturer thought 5000k would be a better fit in homes and etc.





> 5500 is typical daylight...the longest part of the day where it stays the same. but daylight ranges from 2000-3000 at sunrise through to 6500-7000 for an overcast day.
> So to make everything match they set film stock to 5600k as a standard and made professional lights at that standard.


\
I "suppose" the best "natural" def..


> The sun closely approximates a black-body radiator. The effective temperature, defined by the total radiative power per square unit, is about 5,780 K.[5] The color temperature of sunlight above the atmosphere is about 5,900 K.[6]


And of course add scattering.. One could go off the deep end in analysis:
https://www.google.com/url?sa=t&rct...kw9OZC5KA&sig2=3veEl0KX7LL9oPtrTMLS7A&cad=rja

Pick one..


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## Freemananana (Jan 2, 2015)

Most of us do not utilize different color spectrums to mimic the sun's change throughout the day. Most stick to 5000-6500K 'natural sunlight' and put it on a set timer. I would aim for 3000K for sunrise and 10000K for sunset. You'll have better options with LED lighting and using RGB LEDs. Then stick with 6500K white LEDs for the daylight.


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## pipelayer (Sep 24, 2013)

@Jeff - that makes sense since you are controlling individual LEDs. thanks! BTW, if you start and end around 660nm, where are you in the middle?
@Freeman - thanks for the input, So I am guessing it really doesnt make much of a difference for actual growth and is just more aesthetic.


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## Freemananana (Jan 2, 2015)

pipelayer;[email protected][B said:


> Freeman[/B] - thanks for the input, So I am guessing it really doesnt make much of a difference for actual growth and is just more aesthetic.


Pretty much nailed it. Some sunset/sunrise features are for our pleasure. Fish probably enjoy them too, but not nearly as much as we do. The plants really don't seem to care. They mostly want the right color spectrum and many have had great success with the 5000K-6500K.


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## jeffkrol (Jun 5, 2013)

pipelayer said:


> @*Jeff* - that makes sense since you are controlling individual LEDs. thanks! BTW, if you start and end around 660nm, where are you in the middle?


Never mesured it and it actually changed over time, by switching the ratio of WW to CW white LED's
Assuming a cancelling effect of the red/blue ones best guesstimate is I went from about 5000k (before switching diodes) to now running close to 6500k (current config. on the 40).
There is a "trick" to LEd's sort of.. Not all equal K's "look" the same..since it is just an average..The cheap 6500k emitters had a def. "blue tone". My current 6500k emitters don't seem to possess such "toning"..I've found that in 3500- 4000k emitters as well. Some just "look" more right.. 
Advantage of 1)DIY and 2)multiple channels..

as is I can still "dial in" almost any K... On current "full" (all colors, all channels) as I alluded to, is probably just north of 6500k..





pipelayer said:


> @*Freeman* - thanks for the input, So I am guessing it really doesn't make much of a difference for actual growth and is just more aesthetic.


Yes and no really. Depends on how many hairs you split.. A "Natural" progression of light temp. would, in an unqualified sense, play into the "Natural" rhythms of a plants internal chemistry BUT I wouldn't hold too much stock in that "assumption"

sooo Yes mostly aesthetics...


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## pipelayer (Sep 24, 2013)

Thanks guys. There is a lot too learn regarding lighting and your help is much appreciated. 

Ill probably have some variation from morning to night but Im not going to worry about it too much.


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## jeffkrol (Jun 5, 2013)

I find it more overall beneficial not to have the lights "snap" on and off (my fish really hate it) then worry about color temp, though I do quite enjoy my sunsets.. 

also keep in mind "natural" is not always optimal.. Nature does a lot of compromising..


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## pipelayer (Sep 24, 2013)

> "natural" is not always optimal.. Nature does a lot of compromising..


This is a great piece of advice.


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## Freemananana (Jan 2, 2015)

I have a blue LED moonlight that I turn on prior to my main lights. It is just on a timer for 30 minutes before my main lights and then 30 minutes after my main lights. I turn it off for the middle part of the day, as it isn't needed. But it breaks up the intense FULL SUN lighting.


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## Kathyy (Feb 22, 2010)

It's personal taste and the fish would be fine with 15 minute ramp up/down. I want to be able to see in the tank when I am in the room so use low light in the morning and after dark to keep the tank from being a black hole in the room.

Since my LED has 4 channels, CW, WW, R and B I do have fun making up different colors for different parts of the day but it is not important at all. 

In the morning no point in a fancy colored ramping up, 15 minutes to enough light so I can see into the tank. Noon comes early as the room is so bright anyway and afternoon lasts until an hour before lights out but I reduce the % power just so the tank looks lit. I do enjoy making up colors for late afternoon to dark though. For golden late afternoon I lose the B channel over 10 minutes, then a warm glowing sunset is after WW is ramped to zero then lose the red so twilight to night is the CW ramping down.

Other than that I am looking for the tank to replicate sunlight whatever that is here. If I look at an orange platy in the tank and out in full sun I want the color to be the same. I want my mystery crypt leaves to look the same, the rocks, the Congo fins to look natural rather than super saturated. Turns out I need more R than B and more CW than R for that to happen.


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## pipelayer (Sep 24, 2013)

That sounds pretty cool. I guess I will just make sure to keep a solid "sunlight" on the tank for an appropriate amount of time and then just mess around with spectrum and intensity in the evening for my own visual appeal.


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## klibs (May 1, 2014)

IMO around 6000K is the way to go. Looks best if you have some reds in your tank. Too warm and the greens don't pop and too cool the reds get washed out. I have BML Dutch 6300 fixtures and they are a great looking light. Previously went with the 10000K from them and was unhappy because it was too cool looking.

Personal preference when it comes down to it... plants will grow fine as long as you have good spectrum.

Also the user that says that not all temperature light looks the same is correct. One manufacturer's 6500K fixture might look cooler than another's 6500K. It all comes down to the 'average' temp I think and the mix of LEDs can alter how it looks.


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