Finding my Kelvin Temperature?

[echoofformless]

Natural sunlight goes through a whole range of color temperatures depending on the time of day, the time of year, the latitudinal location, the weather, and the surroundings.

In other words say it's noon in Manhattan at midsummer on an overcast day. The color temperature of the light will be very high. One because of the clouds filtering out a lot of the lower spectra like reds, oranges and yellows. Two because the higher the sun gets in the sky, the less atmosphere there is between you and the sun to filter out the higher spectra like blues and violets. Three because the buildings are often light colored and highly reflective - enhancing the natural color rather than absorbing and changing it.

Now picture blue skies on midwinter at sunset on a tropical island. Lots of reds, oranges and yellows being absorbed by a canopy of palm trees. Getting the idea?


Plants benefit from almost all of the different spectra that the sun provides. Not to mention each individual plant has specific preferences.

The reason why 5000-7000k are the "plant" bulbs is because these are the ones which are closest to the overall average of daylight temperatures while also being pleasing to the eye. Think of it like how supposed community aquariums are classically meant to be at around a neutral pH.

But to complicate things even more, consider the fact that plants like to have peaks at certain key ranges of the spectrum - and the kelvin rating of a bulb only indicates the overall color of the light it produces. In other words two bulbs rated at 6700k may be very different when their spectrum is analyzed, with peaks and valleys in certain areas. Some of those areas are more important than others. A bulb with strong peaks in the red and blue will be more beneficial to your plants than one which has weak ones.

 

[livingword26]

One
Three
You know the saying about opinions but IMHO the blue actinic bulb may be beneficial with your freshwater aquarium.
The blue light accelerates the production of chlorophyll by the plants.
I have two 7100K bulbs in my lighting system.

Interesting, I have never heard that. A 7100k bulb may or may not have a lot of blue. What kind of bulb are you using, and are there any links that describe the beneficial aspects of the actinic for plants?

 

[Star_Rider]

I always tell em..it isn't about the K rating..it's about the spectrum .

 

[jones57742]

I always tell em..it isn't about the K rating..it's about the spectrum.

star_rider:

I am just noting and not being argumentative here but:

1) I originally "just flat could not understand" why bulbs were not rated via wave length instead of K;

2) after getting back into my quantum mechanics books (has been 32 years since one of them had been opened) and research on the internet I achieved what I believe to be an understanding;

3) The light spectrum emitted by a bulb is not normally distributed about a given frequency but is distributed in general accordance with black body radiation;
http://en.wikipedia.org/wiki/Normal_distribution
http://en.wikipedia.org/wiki/Black_body

A 7100k bulb may or may not have a lot of blue.

A 7100K bulb, by definition, does emit blue light as observed by our eyes.
(I have two (one each in my PCs)).

What kind of bulb are you using

My current tank lighting is 300W of MH and two PC's which yield 260W.

Mh - 1063
http://www.marinedepot.com/ps_Aquar...usa_sunpod_powerpaq_hqi_lamp_lunar_light.html

PC - CU01013
http://www.marinedepot.com/ps_Aquar...nt_current-usa_satellite_sunpaq_fixtures.html

Interesting, I have never heard that.
, and are there any links that describe the beneficial aspects of the actinic for plants?

Blue light is responsible primarily for vegetative (leaf) growth
http://extension.oregonstate.edu/mg/botany/light.html

Blue light responses: Many plant responses are regulated by blue light, including phototropism, stomatal opnening and chlorophyll synthesis. The last step of chlorophyll synthesis requires high levels of blue light. The other blue light responses are triggered by lower levels of blue light
http://www.mobot.org/jwcross/duckweed/phytochrome.htm


livingword26:

These are not the pages which I reviewed in my original research but I am old and cannot find these pages (which are much more descriptive).

TR

 

[livingword26]

star_rider:

I am just noting and not being argumentative here but:

1) I originally "just flat could not understand" why bulbs were not rated via wave length instead of K;

2) after getting back into my quantum mechanics books (has been 32 years since one of them had been opened) and research on the internet I achieved what I believe to be an understanding;

3) The light spectrum emitted by a bulb is not normally distributed about a given frequency but is distributed in general accordance with black body radiation;
http://en.wikipedia.org/wiki/Normal_distribution
http://en.wikipedia.org/wiki/Black_body



A 7100K bulb, by definition, does emit blue light as observed by our eyes.
(I have two (one each in my PCs)).


My current tank lighting is 300W of MH and two PC's which yield 260W.

Mh - 1063
http://www.marinedepot.com/ps_Aquar...usa_sunpod_powerpaq_hqi_lamp_lunar_light.html

PC - CU01013
http://www.marinedepot.com/ps_Aquar...nt_current-usa_satellite_sunpaq_fixtures.html




Blue light is responsible primarily for vegetative (leaf) growth
http://extension.oregonstate.edu/mg/botany/light.html

Blue light responses: Many plant responses are regulated by blue light, including phototropism, stomatal opnening and chlorophyll synthesis. The last step of chlorophyll synthesis requires high levels of blue light. The other blue light responses are triggered by lower levels of blue light
http://www.mobot.org/jwcross/duckweed/phytochrome.htm


livingword26:

These are not the pages which I reviewed in my original research but I am old and cannot find these pages (which are much more descriptive).

TR

Thanks for all your time. I will research your links.

 

[loaches r cool]

Actinics could be somewhat useful. If you look at the action spectrum of photosynthesis youll see peaks in the blue range. For example here are some graphs showing the absorption spectrum:

from http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html

Now look at actinic it looks like:

This happens to be a bulb for sale on marine depot http://www.marinedepot.com/ps_viewItem~idProduct~GL2143~tab~1.html

You can see that the spectrum does indeed fall within the action spectrum for photosynthesis. But its lacking over 50% of the spectrum offered by daylight bulbs, or actually lacking closer to 80 or 90% perhaps. So they are not a good choice alone, or if your trying to make the most efficient setup for growing plants. But all actinics are not equal. Some actinics peak at shorter wavelengths yet, with a lot of energy in the 300's of nm. In that case most of that energy is not useful at all, photosynthesis drops of sharply less than 400nm.

The reason that actinic is sold for marine tanks is because light in deep marine water is mostly blue. So for those situations, the high Kelvin and actinic light is the natural light. For freshwater plants, that are often in just a couple feet of water, the spectrum of light is pretty much the same as we see it, usually in the 5,500-6,000K range.

K values are often overrated and also very inaccurate. Often times a 3500K bulb or a 15,000K bulb will work as well or better than the common 6500K choice. So basically dont worry to much about it. Get what you like, half of the choice is aesthetics. Its the wattage thats going to be of more importance for the most part.

 

[livingword26]

I thought this might add to the discussion. Here is the color analasys for 4 coralife t-5 bulbs

First the Actinic

Next the 6700k

Next the 10000k

And finally their full spectrum (That comes in the freshwater combo light)

 

[livingword26]

What would be interesting is if someone could find an analysis chart of what kind of spectrum algae prefers.

 

[Reefscape]

Saltwater Reefs- 20,000K.
Freshwater Plants - 6,700K.

Plants require a different kelvin rating for optimum plant growth, this same rule applies for corals as they need a stronger, more intense light output.

Actually, for optimal coral growth, 6500k is the ideal "k" to choose...

Thanks

Niko

 

[loaches r cool]

What would be interesting is if someone could find an analysis chart of what kind of spectrum algae prefers.

Algae uses photosynthesis... meaning it will be about the same. The difference being that algae I believe has more accessory pigments so it can utilize a broader spectrum of light. I believe I read somewhere that cyano can utilize green wavelengths which few plants can. Algae and plants are very similar. Think of it like weeds in your garden. The weeds and veggies use the same light and same nutrients. Weeds are just more opportunistic and when the conditions arent ideal and veggies arent doing well the weeds sure still can be... same thing with algae.