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Part 2 of Measuring Photosynthesis & Consumer Interpretation: PAR, Lumens, PPFD & DLI

Words and images by @SuperFunker.

Part 2, Lumens

Lumens is a measurement of total light emitted by a source, but it's only a narrow representation of the PAR spectrum. As defined by the LI-COR LI-210R Photometric Sensor, the spectral response is a weighted measure designed to rationalize light associated with peak human sensitivity (555 nm). This is ideal for testing household, office and public lighting, but it's a limited gauge for assessing the intensity and effectiveness of horticulture lights.

Consumer Interpretation of Lumens

Although lumens primarily measure the intensity of green and yellow light, it's possible to glean a couple obvious conclusions. Lumens may indicate whether a grow light:

  • Emits a wider bandwidth and has the capacity to stimulate Anthocyanin.
  • Emits green and yellow light and has the capacity to reach shady areas of a crop.
  • Emits green and yellow light and has the capacity to improve quantum yield.

    In order to provide context for assessing the significance of lumens, access to the corresponding grow light spectrum is required. For example, a grow light that boasts of high lumens, may have an inefficient spectrum if most of its light is focused from 500 to 600 nm. An excessive amount of green and yellow light is great for human vision, but could limit the development of flowering/nectar-producing plants. Flowering plants typically perform best in an environment that's dominated by flowering light (600 to 700 nm). Therefore, a high lumens value can be associated with an inferior grow light.

    In contrast, the ZenPro 400plus emits 38,000 lumens and a full-spectrum in which orange and red light are dominant. In this example, the lumens value is an indication of a strong green and yellow signature, but within a well balanced spectrum.

    Words and images by @SuperFunker.

    Copyright © 2018   Zenith LED Grow Lights & ActionGroove Media Limited.


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