Marijuana Light Spectrum

S

SCRIBZ

Active Member
So Im using a 400watt HPS, a 175watt MH, 2 40watt WARM WHITE flouros, and 2 40watt COOL WHITE flouros....USED TOGETHER throughout most of the growing period.....

IS THIS A GOOD IDEA???? my plants are looking wonderful!!!!!
 
BuckTheSystem

BuckTheSystem

Well-Known Member
babygro said:
hiya daydrops

Forget 'brightness' it's not relevant.

The suns 'real' kelvin temperature is somewhere around 5,800 degrees kelvin, but because the sun is not a perfect 'black body' (the standard for calculating kelvin temperatures of light) its adjusted kelvin temperature is somewhere around 6,400 degrees kelvin.

6,400 degrees kelvin is predominantly 'bluish-white' light and this is the best kind of light and kelvin temperature for vegetative growth - primarily because in nature the time of year Cannabis is in vegetative growth is during the long hot days of summer where the suns daylength is the longest and receives the most 6,400k light. The reasons it changes for flowering is again because of the predominance of the kind of light found from the sun when Cannabis enters it's floral stage - usually at the start of Autumn or Fall when the days get shorter and the nights longer thus reducing down the daylength significantly. Sunrise and Sunset account for almost 50% of the suns light during the short days of Autumn/Fall and sunrise and sunset are made up of almost entirely red spectrum light due to the angle of the suns rays hitting the earths surface. Therefore as sunrise and sunset account for almost 50% of the sun total light output at that time of year it necessarily follows that 50% of that light will be entirely in the red end of the visible spectrum - hence the 2,700k colour temperature being favoured for flowering. In reality a mixture of red and blue light is required in flowering due to the other 50% of the spectrum being more blue in colour.
Click to expand...
So, is it best to use a mix of both cfl's when vegging? Will it help the mother, seedlings, clones at all by mixing?
 
erised

erised

Active Member
Mixing is good... no mixing is great.
The more broad the spectrum, the better. During veg you want more towards the daylight/daylight+blue end and during flower you're gonna be diggin more towards the red end of the spectrum.
 
C

Cyphen

Well-Known Member
FilthyFletch said:
Well this confuses me since Kelvin is a measure of heat and not light such as Lumnes and lumnes are what matters for light or is Kelvin used in regards to color spectrum measurments some how?
Click to expand...

Filthy-

The Kelvin spectrum is commonly used to represent the visible spectrum of lighting. Here are two articles regarding:

Kelvin Color Temperatures
Flourescents and Kelvin Myth

To quote the second article:

"Sunlight and incandescent lamps are very good "Black Body Simulators"- they behave in a manner very close to the predictable spectral distribution of the "Theoretical Black Body Radiator." With these light sources, one need only measure the energy at two places in the spectrum - red and blue - to determine the Kelvin. However, when the light source has an "interrupted" spectrum - as do all fluorescent and discharge lamps - it is not correct to describe that light source as having a Kelvin temperature."


So yea, it is applicable, but not really appropriate.
 
A

azorespepper

Active Member
this is my 1º growroom 1.3mt longer,1.0mt large and 2.00mt high with 16 plants under 1*400w,2*100w and 3*70w...alll hps !!is that enough ???? they are on the 2º week flowering !! and now i got 2 *150w vialox nav ts super 4y(double ended) on adding them... ???!!!
 
Last edited:
Trichome9

Trichome9

Member
So, the optimal light temperatures for Vegetation and Flowering would be 6500k and 2700k, respectively?

And I should try to get the highest wattage I can (Within reason), so as to get the most Lumens, right?
 
Natures Cure

Natures Cure

Active Member
FilthyFletch said:
Well this confuses me since Kelvin is a measure of heat and not light such as Lumnes and lumnes are what matters for light or is Kelvin used in regards to color spectrum measurments some how?
Click to expand...

I think your kinda right as color can be measure in temperature, right?

Correlated Color Temperature (CCT)
The apparent color of an object changes as the temperature increases. All objects emit light when sufficiently hot. The brightness and color of the light emitted is a function of temperature. If the object is hot enough to glow, like a tungsten lamp, it is said to be "incandescent". Incandescent sources that emit radiation with 100% efficiency are called "Black Body Radiators" or Planckian Sources. An ideal black body glows with a color that is solely dependent on the object's temperature (in ºK - Kelvin) and therefore, its temperature can be used as a color standard. This concept of color temperature can be applied only to sources that are black body radiators.
On the CIE chart (figure 2), the chromaticities of black bodies at different temperatures fall on the Planckian locus. Other sources that have chromaticities lying near this black body can be described as having a "Correlated Color Temperature", CCT. The CCT of a source is the temperature of the blackbody radiator which has the chromaticity most similar to that of the light source. For example, if a source has a CCT of 3200 º K, that means it has the same color that a black body would have if heated to 3200 º K. Sources with higher color temperatures have maximum intensities at shorter wavelengths. (6500 ºK is the standard for white light used for most white LEDs)​





FIG 2 - CIE Chart w/color temperature​

Currently, the most accurate method for measuring color is by using a Spectroradiometer. This device performs a complete spectral power distribution of the source being measured from which all photometric, radiometric and colorimetric parameters can be mathematically calculated. The wavelength accuracy of the equipment should be better than .5nm with .1nm preferred. There are several factors that can affect the value obtained. One of these is temperature. As the ambient temperature rises, so to does the LED wavelength. This increase will typically be from .1nm/ºC - .2nm/ºC depending on the type of LED used.​

Here is a link to wiki on black bodies!​



:peace: and :weed:​
 
applepoop1984

applepoop1984

Well-Known Member
can u edit that chart to show which spectrums the plant does nto use? id say it would be 3200-4500 would be un-useful (lol) light spectrum
 
rak1

rak1

Active Member
Hi, Im a newb to growing, can anyone anwser this? I have a cfl 100w from walmarts on a couple new plants, It says Its 16000K.
Am I to far off from 5500 k , or would this CFL be ok to use?
 
S

smoke10joints

Member
lol spectrum looks right, but the boxes you added were a bit off lol
pauliojr said:
It has been brought to my attention that more then a few people have been getting confused on light spectrums and which ones are better for which stage. Below is a picture that I have edited from Marijuana Seeds Search Garden that divides the kelvin light spectrum in half and tells you which one you would like to use more in what stage. It is posted in another topic and it was brought up to do this. I hope this helps some people out down the road. Thank you all (especially MR. ISSUES).

Click to expand...
 
S

smoke10joints

Member
is it the 27 watt but replaces 100w?? but thats how many lumens you have, thats not color that number will have a k next to it. either way your gonna need alot more of them as your grow continues
 
You must log in or register to reply here.
Top