What is the lux I am looking for at plant level seedlings
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Lux is only for light visible to the human eye, you want par readings.
| Growth Phase | PAR Level (PPFD) |
|---|---|
| Seedling / Clone | 100 – 300 |
| Vegetative | 250 – 600 |
| Bloom / Flowering | 500 – 1050 |
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On my lux meter, I usually start them at 5k. I definitely wouldn’t go more than about 8k until they have maybe a 2nd set of leaves. Like @DougDawson says, PAR is better. Lux is ok for approximation, but not the ideal measurement scale.
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I came across a really well written reddit post about LUX & Lighting I’ll link it.
It’s really inofrmative written by HandsOnComplexity
https://www.reddit.com/r/HandsOnComplexity/comments/17nxpy/using_a_lux_meter_as_a_plant_light_meter/
Here’s a whole bunch of his links on a range of topics I haven’t read them all but I’m sure they’re good
https://www.reddit.com/r/HandsOnComplexity/comments/s4wcmh/sags_open_access_cannabis_links/
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There’s a couple good points in there.
Only use a lux meter with white light sources, not “bluple” red/blue dominate grow lights
To expand on this… PAR and LUX are both adjusted for spectrum. Our eyes are most sensitive to green spectrum, being the center of the visible range of wavelengths. So lux disproportionately weights green photons as being higher lux, as compared to blue (shorter wavelength) or red (longer wavelength). PAR = photosynthetically active radiation, which weights specific regions of chlorophyll photoactive blue and red as higher than green.
It requires either color correction filters to calculate either lux or par. The filters have different properties. Because blurple lights have red/blue diodes and no green light, it creates a low lux reading that can still be high par. In practice, there is actually no universal correction factor between lux and par for this reason. Even “white” LEDs still have much stronger intensities in red/blue than green. Different color temperatures for the same PAR will also read different LUX.
- 5 klx -unrooting cuttings (you don’t want too much light)
- 15 klx -lower end for seedlings (more light and/or higher CCT if stretching)
- 25 klx -lower end for veging (robust growth, keeps stretching down)
- 40 klx -lower end for flowering (you don’t want loose buds)
- 100 klx -cannabis yields are linear to around this point under ideal conditions
Cannabis veg >25,000 lux. Cannabis flowering >40,000 lux. Use more light if there is unwanted stretching in veg, pump up the volume in flowering. Cannabis starts light saturation starting around 100,000 lux under ideal conditions.
IMO too high. 15k is not a number I would use on seedlings, too high. 25k is a number I only hit at a fairly mature veg state, upper end for me. 40k for flower for me is a good number for flower, but a middle range for what I typically use 35-45k. 100k is unimaginable for me… seems like you will get weird revegging stuff and bleaching if you get even close to that.
Maybe their meter reads differently than mine. On my meter, I use the low end of all of these numbers.
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I certainly have nowhere near the experience you have so thanks for sharing 
I find these videos helpful too
&
Have you gone through these video…what are your thoughts on these videos ?
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