Lighting question

[Michael]

I am preparing to upgrade my lighting from a double regular Fluorescent
to a double compact fluorescent.

I notice that there is a difference between marine applications and
freshwater. Marine uses 10,000K bulbs and freshwater uses 6700K bulbs.

Why the difference? Wouldn't the Marine bulbs work better on a
freshwater planted aquarium than the freshwater bulbs?

Thanks in advance

[Glenn]

While others will be able to give a more technical response, the short
answer is no. Marine bulbs are used to simulate the light wavelengths found
at the depth of a typical coral reef. The 10,000k bulbs are a little bluer
which makes them appear whiter. The 6000 - 67000k bulbs are more yellow,
and mimic the sunlight closer to the surface.

Corals seem to prefer the actinic blue light at or above 10,000 but I belive
freshwater plants prefer the 6700k.

"Michael" > wrote in message
t...
>
> I am preparing to upgrade my lighting from a double regular Fluorescent to
> a double compact fluorescent.
>
> I notice that there is a difference between marine applications and
> freshwater. Marine uses 10,000K bulbs and freshwater uses 6700K bulbs.
>
> Why the difference? Wouldn't the Marine bulbs work better on a freshwater
> planted aquarium than the freshwater bulbs?
>
> Thanks in advance

[carlrs]

Glenn wrote:
> While others will be able to give a more technical response, the short
> answer is no. Marine bulbs are used to simulate the light wavelengths found
> at the depth of a typical coral reef. The 10,000k bulbs are a little bluer
> which makes them appear whiter. The 6000 - 67000k bulbs are more yellow,
> and mimic the sunlight closer to the surface.
>
> Corals seem to prefer the actinic blue light at or above 10,000 but I belive
> freshwater plants prefer the 6700k.
>
> "Michael" > wrote in message
> t...
> >
> > I am preparing to upgrade my lighting from a double regular Fluorescent to
> > a double compact fluorescent.
> >
> > I notice that there is a difference between marine applications and
> > freshwater. Marine uses 10,000K bulbs and freshwater uses 6700K bulbs.
> >
> > Why the difference? Wouldn't the Marine bulbs work better on a freshwater
> > planted aquarium than the freshwater bulbs?
> >
> > Thanks in advance


I agree.

Here is more information from one of my articles about this:
Although I do not believe all the manufacturers are totally honest
about true Kelvin output, I believe it should be considered. Kelvin is
used to define the heat or energy output of a bulb and if this is
applied to two 36 watt PC bulbs, one 6500K the other 10,000K (often
daylight or power glow), the 10,000K bulb has a higher energy output.

A few notes about Kelvin:
* Plant chlorophyll absorbs light at wavelengths of 400 to 700 nm
* The lower the "K", the more yellow the light appears, such as a
4500K bulb.
* The higher the "K", the more blue the light appears, such as a
20000K bulb.
* The human eye sees mostly sees light around 5500K.

The Nanometer scale and Kelvin temperatures come together when applied
to aquarium lighting this way; Natural sunlight on a clear day
registers at 5500 Kelvin degrees. Kelvin temperatures less than 5500
become more red and yellow and the higher the Kelvin temperature the
more blue the light is. Most photosynthetic invertebrates should be
kept with lamps of a 20000K rating. Actinic emits a fluorescent blue
light and is usually used as supplemental lighting. Not only is actinic
lighting beneficial to photosynthetic invertebrates, it is also
aesthetically pleasing to the eye when used to supplement "daylight"
lighting. Freshwater aquarium plants benefit from lighting with a
Kelvin temperature in the range of 5500 - 6500 degrees. Freshwater
plants prefer light with more red and yellow in the spectrum. What the
exact Kelvin output of an aquarium bulb is takes a little faith in the
manufacturer (at least in my opinion), as it is difficult to test each
manufacturers claims of Kelvin and the application of Kelvin to
aquarium bulbs takes a little bit of scientific stretching (based on
the definition of Kelvin).

For more information and a graph, please see this article:
http://www.americanaquariumproducts.com/Aquarium_Lighting.html

Carl