LED vs. HPS Light Intensity -- What You Should Know

I have been asked in an E-mail to use a light meter from HTGSupply.com to compare a 90W UFO LED to a 600 W HPS. 

What you should know is that using a light meter is not the best way to compare these two lights.  The benefit of  LED's is that they emits a very specific wavelenght of each light, this is why there are individual colors of LED lights, because each LED emits such a narrow range of light it looks like a single color to our eyes.  An HPS (or MH) on the other hand, emits a greater light intensity.  The light meter will show a higher output of light from the HPS but the problem is that not all the light is available for plants to use during photosynthesis.  Translation, a lot of the light is wasted and a lot of the energy to create that wasted light results in heat generation too.  This is why LED's CAN BE more efficient, they use less energy and only emit light that plants need to do photosynthesis.  The reason I say CAN BE in caps is because it is possible to make an LED that is less expensive, but it emits light that is NOT in the optimal wavelenght for photosynthesis.  This means the light will not promote good plant growth.  The reason this is a problem is that the pigments that absorbs light in plants for photosynthesis are different than the three pigments we have in our eyes that absorb light and let us see color.  Translation, what we see as red is not necessarily the best 'red' that plants need to conduct photosynthesize.  I know that the Tri-Band technology from HTGSupply.com is tested and I personally have grown numerous plant species from seed to flowering under it.

Good Growing
Dr. E.R. Myers