A lumen is a measurement of the amount of light radiated by a source. Cannabis plants need at least 30.000 lumen per 3 square feet. More is better.

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More lighting related terms:

Lighting | Light cycle | Dark cycle | Light shortage | Light distribution | Light spectrum | Blue light | Red light | Nanometer | Light tight | Lux | Reflecting light | Lamp height

HPS lights | HPI lights | LED lights | Compact fluorescent lights

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