Color Temp

[soko]

Is it all about looks or do your plants really care?

There are so many different temps, 5000K, 6700K, 9325K, 10000K, 50/50, Actinic, what do they all mean? One is blue and one is red, okay, so what? How do you decide which lights to pick, every site I find just says the same thing by telling you what the terms mean but nothing about how it effects your plants, fish, etc.

I am still planning my 55 gallon tank (freshwater) and hope to have about 3wpg and plants that will benifit accordingly. This kelvin jive has got me all confused now.

Thanks for any help

[Wasserpest]

Hi soko, welcome to the Planted Tank!

With 3 watts per gallon you will have sufficient light to grow lots of plants. The exact color temperature (Kelvin) is not that important for plants or fish. Plants use red and blue parts of the color spectrum, but this can not be expressed in Kelvin. Some bulbs are very good for plant growth, like the 9325 Kelvin bulb you mentioned, others are missing parts of the spectrum and are less useful, like actinic bulbs.
Part of choosing a particular color temperature has to do with personal preference... all about looks, as you say. Avoid bulbs with a temp lower than 5000K because they seem to encourage algae growth and make the tank look very yellowish. As you get higher in K the light looks whiter and finally looks bluish white. I like the looks of a 10000 K lighting, others prefer warmer tones, 5000 to 6500 K. In any case, that is not related directly to how good they are for plants. Intensity and spectrum are what makes plants grow.

[malkore]

all I'll say is that color temp USED to be a decent indicator of whether the bulb would put off the right spectrum. However nowadays they do tri-phosphor coatings and other neat tricks to make Kelvin ratings almost useless. You can generally say if it's between 5000 and 10000k, it should be usable by plants.
actinic isn't in that range and shouldn't be used in a fresh, planted tank, unless you really dig blue water.

[soko]

Great replies, makes alot of sense. Thanks

I have decided to buy two kits from ahsupply, a 96 watt 1000k and a 13 watt red or 5000k to put on like 30 min before the main light to simulate a sunrise, sunset. (55 gal tank)

Does this sound resonable?

I decided I will just leave room in my custom hood for another 55 watt light fixture if I feel sometime in the future that more light would be worth it, being my first tank, I decided to take it slow.

Thanks agian!

[Zurp]

Take a look at the links I posted in this post...
http://www.plantedtank.net/forum/viewtopic.php?t=4066

You will find a lot of T5 links there, but some are just on lighting in general... The last few do some in depth explaining about spectrum and visibility.

[05dr]

here is a thread i have been working on with enough links of different color temps to make anyone's head spin. just find what you like and balance it with appropriate color spectrums for freshwater plants and you'll have winner!
http://www.cichlid-forum.com/phpBB/v...ic.php?t=29064

[Seamaiden]

Actually, color temperature, rated in Kelvin, is and can be a very useful (in reefing it's VITAL information) tool in determining how closely a given bulb matches the spectrum of the sun. That is to say, how closely does it match in terms of what wavelengths, and where it peaks. This is not at all a measure of intensity, a.k.a. lumens or lux. 5000K - 6200K (five thousand to six thousand, two hundred Kelvin) is the base standard for a match to the sun (and sunlike stars) of violet through red wavelengths (400 - 700nm).

This link is speaking directly to marine aquaria needs, however, the information is true no matter the application: http://www.wetwebmedia.com/marine/setup/lighting/

[Seamaiden]

Oh yes, a VERY popular supplier is http://www.hellolights.com/

[2la]

Originally Posted by Seamaiden

Actually, color temperature, rated in Kelvin, is and can be a very useful (in reefing it's VITAL information) tool in determining how closely a given bulb matches the spectrum of the sun. That is to say, how closely does it match in terms of what wavelengths, and where it peaks.

I totally disagree. It tells you very, very little. You can't even compare the spectral output of fluorescent tubes, which produce emission spectra, with that of the sun, which produces a continuous spectrum (ignoring, for a moment, the minor absorption spectrum produced by the atmospheric and cosmic gases that sunlight passes through on its way to your eyes). All color temperature tells you is the overall color effect of a particular tube--and it doesn't even do that particularly well. It will NOT tell you how closely it replicates how objects appear under sunlight (use CRI, or color rendering index, for that instead). Why? Because color temperature tells you nothing about spectrum (especially emission spectra), and all 5000K or 6500K tubes are NOT created equal (go here, for example, and see how the spectra of the GE Chroma 50 and the GE SPX50 differ immensely--as do their overall color! Color temperature is the least reliable specification to look at when it comes to comparing bulbs!). Thus, if you put a rummynose tetra under the SPX50, you can expect its crimson head to appear considerably more brilliant than it would under the Chroma 50 owing to the SPX50's stronger red emission peak.

[Zurp]

In my opinion, I would try to appease both, if economically possible.

Animal creatures, to some extent, prefer natural sunlight spectrum. Not exactly the same color, but the same spectrum pattern. Some are needed for vitamin usage, some merely for mood.

Plants, on the other hand, generally prefer reds and blues more. The ratio is about 4:1:5 Blue:Green:Red. Don't start a debate... I said generally... Some plants have unique tastes...

The more important thing is volume and intensity. Animals do not like to be blinded, yet plants don't care. Plants don't like excess heat, animals are more tolerable... They can find shade, and regulate...

So... I would try to get at-least one full spectrum (One closest to the suns pattern) and one plant/aqua lite... at least! Plant lights do not have enough full spectrum, and full spectrum's are not exactly strong enough for spectacular plant growth, or for penetrating water.

If you intention are more toward Critter or Plant... get two of those styles of lighting.

Full Noon Spectrum = Nearly Pure White (Slight Bluish Hue) (6500K - 7000K)
Plant Light = Reddish Violet (Warm White) (4000K - 5500K)
Aqua Light = Bluish White (Coral Light) (9000K - 10000K)
(This is just a major generalization that I observed.)

Here comes the debate...