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Old 04-30-2019, 02:46 PM
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Default Lux as a light meter?

I have an app for the mobile that helps me calculate the lux I get from different lights, the 50w led seems to be what it gives (exceeding the maximum of the app to 50cm) if someone uses this way I measure and grow well the plants I would like to know how many lux has and how much
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Old 04-30-2019, 03:06 PM
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Default Re: Lux as a light meter?

so I can't give numbers, but I do know a little about how plants use light.

the issue with lumen/lux is that it's a measure of light corrected for the sensitivity of the human eye.
the wikipedia page mention the exact details and formulas:

but what the human eye sees best is different from what plants use best.
the absorption peaks of chlorophyl(the major compound taking care of photosynthesis, there are some other minor ones like carotenoids) has absorption peaks in the red and blue parts of the light spectrum(which is why those plant growlights look purple, it's red and blue light mixed together. and most lamps meant for humans look more yellow, because that way you get something that looks bright to us with minimal electricity usage). the sensitivity human eye just has 1 big peak in the yellow part, the part used least by plants.

what you want to know is PAR(photosynthetically active radiation), not lux/lumen. and you need to measure that seperately, there's no simple formula to calculate PAR from lux, since it's a different part of the spectrum. 2 lamps with the same lux could have different PAR.
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Last edited by dendrobates frisia; 04-30-2019 at 03:08 PM.
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