MedMan

While searching for light info I found this........



Plant Development is dependent on the specific spectrums of the light source and the usable light energy.
Only 37% of the energy in sunlight is within the wavelength (colors) useful for photosynthesis, while 62.4% is infrared (thermal energy) and the remaining 0.6% is ultraviolet. Photosynthesis in the plant leaf is powered by 1% of the sunlight that falls on the plant, 10% of the sunlight is reflected and 10% passes through the leaf. The leaf will retain 80% which is used for transpiration. Some of the light is re-radiated, while the fraction that remains is used for building building food from the carbon dioxide, minerals and water.


Usable Light Energy of Artificial Lighting compared to Sunlight.

Useable light energy for plant growth is measured in Micro-Einsteins ( micro-mols of photons per meter squared per second). The sunlight reaching our plant is approximately 2,200 micro-einsteins on a cloud-less day and 170 micro-einsteins on a very cloudy day.

For indoor growing under artificial lighting a range of 395 to 500 micro-einsteins is considered by experts at NASA to be minimal energy level for plant growth.

The higher the bulb wattage the further away the plant must be from the light source to prevent environmental heat stress that can cause the plant to transpire too quickly. Excessive transpiring can dehydrate plants leading to wilting and poor growth. Likewise, the further the plant is from the light source the less available useable energy is delivered to the plant. The indoor grower most tune light energy resources as well as other environmental variables for optiumal growing conditions.

Criteria for maximumizing the artificial light energy for photosynthesis

The indoor grower has several options for maximumizing the artificial light energy for photosynthesis, they are as follows:

Use light bulbs that have the highest level Micro-Einsteins per watt (reproducing natural sunlight conditions as much as possible)

Place the bulb as close to the plant as possible to deliver the highest level Micro-Einsteins per square inch (without over-heating the plant)

Filter out infra-red radiation (to use the only the portion of the light spectrum needed by the plant and to reduce heat build up inside of the plant cells)

Chart for Micro-Einsteins per watt of various types of light bulbs.

Here is a chart that can help you in determining the useable light energy for your plants. For optimum usable energy for photosynthesis, select a bulb that has the lowest wattage with the highest usable energy coefficient.

Bulb Comparisons (1)BULB Type: (2)Distance: (3)Micro-Einsteins: (4)Usable Energy Coeffecient

(micro-einsteins per watt)
(1) (2) (3) (4)
Incandescent
100 watt 3 inches 310 3.100
Incandescent
100 watt 6 inches 190 1.900
Incandescent
100 watt 12 inches 65 0.650
Incandescent
100 watt 18 inches 27 0.270
Incandescent
100 watt 24 inches 18 0.180
Incandescent
100 watt 36 inches 9 0.090
Halogen
20 watt 3 inches 1279 63.950
Halogen
20 watt 6 inches 413 20.650
Halogen
20 watt 12 inches 145 7.250
Halogen
20 watt 18 inches 122 6.100
Halogen
20 watt 24 inches 65 3.250
Halogen
20 watt 36 inches 32 1.600
Sodium
250 watt 3 inches 250 1.000
Sodium
250 watt 6 inches 99 0.396
Sodium
250 watt 12 inches 30 0.120
Sodium
250 watt 18 inches 14 0.056
Sodium
250 watt 24 inches 10 0.040
Sodium
250 watt 36 inches 7 0.028
Gro-Lite
100 watt 3 inches 420 8.400
Gro-Lite
100 watt 6 inches 135 2.700
Gro-Lite
100 watt 12 inches 60 1.200
Gro-Lite
100 watt 18 inches 31 0.620
Gro-Lite
100 watt 24 inches 18 0.360
Gro-Lite
100 watt 36 inches 9 0.180
Fluorescent
40 watt 3 inches 52 1.300
Fluorescent
40 watt 6 inches 36 0.900
Fluorescent
40 watt 12 inches 13 0.325
Fluorescent
40 watt 18 inches 7 0.175
Fluorescent
40 watt 24 inches 5 0.125
Fluorescent
40 watt 36 inches 2.5 0.063

For more info-http://www.aeroponic.com/aero65.htm

What there saying is a 20 watt Halogen this type=(http://www.aeroponic.com/aero6c.htm#High-Efficiency%20Lighting) produces more usable light than a 250w hps.

Has anyone actualy used this kind of light???
Any feed back would be appreciated.

Thanks in advance. MedMan

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If your soil is healthy then so are your plants.