dimmable ballests

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pc - Good point about the "actual surface" Sun's intensity, I suppose I meant how intense it is on the planet's surface given environmental conditions as you mentioned (angle/atmosphere etc). This subject always brings the conversation of lumens and spectrum up for me soo......

The amount of light the Sun pounds on us, does in fact, average out to far exceed our indoor grow rooms - primarily because no "sweet spot" exists outdoors and the power of the source. In sunny conditions, massive swaths of the planet receive the 10,000 lumens your referring to - rather than the limited area below our bulbs that create our optimum growth space. Even with naked bulbs we loose intensity after only a few feet. That is the difference I should have clarified better.

We have to consider a few things. First, the bulb manufacturers measure lumens by determining the total output of your bulb - all the way around it. If you were to take a bubble and encircle your light, all the light that passes through that bubble could represent lumens. With a light hood, we are directing those lumens produced on one side of the bulb onto our plants. The other side of our bulb must reflect it's light to reach our plants. This reflection seriously diminishes a large portion of our lumens. Indeed the manufacturer sites massive lumen output - this does not always equate to massive lumen applications in our grow-rooms. The math sure works well but placement and installation have immense effects on efficiency and realistic out-put.

How light falls to the Earth and how we apply light is what I think is important here. Different spectrums of light actually carry with them different lumen intensity. As the angle of the Earth and the atmosphere allow different light spectrums deeper penetration the amount of lumens that reaches us differs. This is a complicated science requiring an understanding of Watts, lumens, spectrum and lux.

Watts refers to how much energy is used to create light, lumens to how much actual light is produced and lux takes into the account the area in which the lumens are spread. (Lux also dictates how humans perceive lights intensity). Spectrum is what type of light is illuminating. As Pc said, under the sweet spot the average 1000 watt bulb produces between 10,000 to 12,000 lumens. However, the intensity of indoor lights diminishes quickly the farther away we get. Hypothetically, a square meter with an indoor bulb 3 feet above it does equal the same lux as outdoors. The lumens at the floor have diminished substantially. I realize our plants grow within this 3 feet I'm referring to but the science remains in terms of light.

Outdoors the Suns wattage is something near 386 billion, billion mega-watts (or something unfathomable like that :)). This outrageous power generates heat and lumens with consistant lux. Given that Earth's atmosphere and environmental conditions are normal, the Sun far exceeds our indoor light's output. It's power generates similar lumens, yet far more lux with no "sweet spot". So yes, we can out-do the Sun's lumens but it needs context. Lumens are merely luminosity (how bright the light is). Per square meter, the Sun can produce between 30,000 and 100,000 lux psm while our indoor lights produce maybe 1000 lux psm. This is where I think things differ. Lumens per square meter is an important calculation for us in reference to calculating growth parameters and possible production but we cannot ignore watts per square meter (irradiance) when discussing comparisons of the Sun and indoor bulbs - it describes a major difference and represents the reasons some of us have produced mammoth plants outdoors and struggle to produce equivalent harvests indoors. The power of the Sun is simply to strong. Yes, typically our indoor environments create consistency and environmental predictability therefore frequently produce high quality marijuana but lumens are only one part of that scenario.

With dimmable ballasts we are lowering not only lumens, but wattage and lux. As lux is already seriously diminished comparatively, dimming the light seems counter productive in my book. As we know different light spectrums carry with them different lumen intensity and if the goal here is to mimic the outdoors, then changing light spectrum seems more important to accomplish that goal.

On the other hand, dimmable ballasts certainly have a place. Vegging to flowering for example (our veg requiring less lumens). Or simply an option to use less power. In terms of replicating seasonal changes in sunlight however, more complicated measures would have to be taken IMO.

Heres a few links to read for yourselves:

hXXp://solar-center.stanford.edu/about/
hXXp://www.energybooks.com/pdf/D1150.pdf
hXXp://en.wikipedia.org/wiki/Lux
hXXp://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10630
 

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