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What is PPF (Photosynthetic Photon Flux)?

  Photosynthetic Photon Flux measures the amount of PAR (photosynthetically active radiation) a given light source emits each second. In practical terms, PPF defines how much usable light a lamp emits. PPF is expressed in micromoles (umol) per second.  


  It is important to note that PPF only measures the amount of PAR a lamp emits, not the amount of PAR that reaches the canopy in indoor cultivation. Light intensity decreases the farther light travels from its source, which means your plants will never receive as much PAR as your grow light can actually produce. To find out the amount of PAR that falls on the canopy, look for the PPFD specifications for your specific lamp.