absorption spectrum, grow light, light absorption, PAR, photosynthesis, PPFD -

Part 3 of Measuring Photosynthesis & Consumer Interpretation: PAR, Lumens, PPFD & DLI

Words and images by @SuperFunker.

Part 3, PPFD

Photosynthetic Photon Flux (PPF) is the total amount of Photosynthetically Active Radiation (PAR) emitted by a light. Measured in micromoles per second (µmol/s), PPF provides a general understanding of a light's full output, but it does not measure the photons that actually reach your specimen. To rationalize the true utility of natural and artificial light, the Horticulture Industry relies on a narrow interpretation of photon delivery by gauging Photosynthetic Photon Flux Density (PPFD). Expressed as micromoles, per square meter, per second (µmol/m2/s), PPFD is an evenly weighted measurement of PAR that falls on a specific spot. As detailed below, the Apogee SQ-500 Quantum Sensor and the LI-COR LI-190R Quantum Sensor employ a balanced testing profile to assess PPFD across the entire PAR spectrum.

Consumer Interpretation of PPFD

When exploring the Grow Light Market, access to objective PPFD data is critical to understanding a grow light's general utility, comparing brands and making an informed purchase. Therefore, all grow light sellers should publish some sort of PPFD assessment in association with a logical context. If a seller posts a single PPFD number, the height of the light is required to provide context. Or, if a seller posts an average PPFD value, the height and area is required to provide context. For example:

  • At a height of 1 foot on center, ZenMatrix 990 peak PPFD is 2,030 µmol/m2/s.
  • At a height of 2 feet on center, ZenMatrix 990 peak PPFD is 910 µmol/m2/s.
  • At a height of 2 feet over an area of 9 square feet (3' x 3'), ZenMatrix 990 average PPFD is 486 µmol/m2/s.

    Words and images by @SuperFunker.

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


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