# What 10.000K light?



## harrykaa (Jan 10, 2005)

Hi there xoshagsox and hiphopn and others,

The 10.000K fluorescent bulb is very commonly sold in Finnish lfs and in common stores for aquarium purposes. These are labelled as FLORA, FLORALUX, TROPICAL etc. and from the brands like SERA, OSRAM, SYLVANIA etc.

The light they emit is claimed to promoto photosynthesis. It has greater amount of blue and red light compared to green.
It has been shown that green chlorophyl absorbs red and blue light much more than green light. This has led to a conclusion that a 10.000K light is best for photosynthesis.

BUT. Few things have been forgotten.
1) Plants (and waterplants as well) do have other pigments also than green chlorophyl. They have yellow and red pigments as well. These pigments need more yellow and green (red pigment) or green (yellow pigment) than blue or red to manage photosynthesis.
2) Take a look at power output of a 10.000K fluorescent bulb. Lets say the input (power consumption) is 36W (which is a 4' or 120cm bulb).
In OSRAM
the basic-type (white 4.500K) output is 2.800 lumen;
the flora-type (10.000K) output is 2.000 lumen;
the comfort-type (warm 6.000K) output 3.350 lumen.
It is very easy to see that the red-blue color has been done by only reducing the green light. The bulb does not emit more red or blue light than the basic-type or comfort-type bulb.

As a whole, the reason to use a wide spectrum light (near white, 5000K-6000K) is very simple one. The plants on earth and in water have evolved during hundreds of millions of years to get best use from the sunlight (5.600K).

If one claims that his plants grow better with a 10.000K bulb, he also states that his plants qrow better than those in nature with sunlight!

BTW. A fluorescent bulb basically emits three main types (wavelengths) of light:
red, green and blue (RGB light).
A human eye sees the light as white when all three are emitted similar to daylight.
A green leaf is green (as a human sees it) because it does not absorb the green light as well as other wavelengths and thus it emits green more. But it does not emit back all the green light!

PS. I have tried using 10.000K lights many times as a primary light source in aquarium. Each time especially green brush algae takes advantage of this, but the higher plants seems to slow down compared to wide spectrum lights. I believe that one should try 10.000K lights but only when combined with wide spectrum lights. And it is better to use only the latter ones.

Regards,


----------



## Husky_Jim (May 26, 2003)

Nice post...


----------



## Handikapped (Nov 5, 2004)

good stuff


----------



## channafreak (Mar 27, 2004)

Yes... Nice post my friend. These northern europeans know their dutch setups.


----------



## Vampor (Feb 15, 2003)

very nice post, worth to be a sticky? questions like these it quite common (i was going to ask this myself)


----------



## DepH (Jan 11, 2005)

I use a 10.000k, and no other spectrum lights is combined.
My plants are beginning to get a bit brown. I changed my Co2 bottle, and it got a bit better.
Maybe this is because of just using the 10.000k light?


----------

