LED Lighting Height


#1

I’m using a 3’ x 3’ x 6’ tent and currently have 2 14 red, blue, orange & white side lights and a 185w Dirt Genie with UV in the center. How high above plants do I need to keep the lighting adjusted? I have read a lot of good about LED’s vs. other types. Do they really perform on a level with one or more alternated light types in terms of yield and total seed to smoke cycle?


#2

LEDs if used correctly provide amazing results rivaling any other light system with a much lower electric bill. The thing is they do need to be used correctly, just as some people do get amazing results with only common CFL florescent lights, but you have to understand the benefits and limitations of the light you are using.

The light height or distance from the canopy to the light with LED lights depends on a few different things including the degree of focus being used in the lensing and the distribution and spacing of the various LEDs of various spectra, as well as the actual power of each individual LED. This maximum close recommended distance is something that should be available from the manufacturer or in the directions that came with the unit.

You might be able to get an idea of the closest distance you could have while still maintaining a full even spectra by having the LED system above something like a white board and see how close you can bring the light while maintaining an even look to the color distribution, if you see areas that are to pure blue and/or to pure red then the canopy would not be getting an even amount of red and blue light on all the leaves and this would be too close of a distance. Most LED systems do not have an even spectra coverage at much closer than about 18 inches, some maybe as close as 12 inches but that is pushing it with any system that uses separate high powered red and blue diodes with any spacing between them, it might work with a system that has full PAR spectra in each individual diode or one that uses almost all pure white diodes. Also depending on the power of the diodes and the degree of lensing there may be no max close distance, low powered LED diodes are not likely to cause problems even at point blank range, kind of like lower powered florescent T8 lights, you can practically have the leaf touching the lights and sometimes not burn them.

BTW, is the 185 watts actual watts consumed by the LED system or is it the theoretical max of the unit because it uses, say – 37 individual 5 watt LED diodes? If it is actual watts you are a little short for the coverage area you are trying to grow in, the extra side light may or might not make up the difference. If it is less actual watts, then you need about a minimum 35 actual watts per square foot with LEDs, but even this general rule can be manipulated depending on how close you can get your light to the leaves as the amount of light the leaves gets dramatically increases because of the inverse square law.