Lux meter reads sun at 130k lux midday. Is it broken?

kreikrei

kreikrei

Active Member
Hey guys.
Just for "fun" wanted too see how bright is the sun, so midday I took my cheap lux meter ( uni-t ut383 - abut 25 usd) to my balcony to check it.

It showed 130k lux, but google says sun maxes out at 100k.

I am assuming my meter is broken or there is something I am missing?

Thanks
 
hotrodharley

hotrodharley

Well-Known Member
kreikrei said:
Hey guys.
Just for "fun" wanted too see how bright is the sun, so midday I took my cheap lux meter ( uni-t ut383 - abut 25 usd) to my balcony to check it.

It showed 130k lux, but google says sun maxes out at 100k.

I am assuming my meter is broken or there is something I am missing?

Thanks
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Well it’s definitely questionable. At best. What type grow light would you be using this on?
 
kreikrei

kreikrei

Active Member
hotrodharley said:
Well it’s definitely questionable. At best. What type grow light would you be using this on?
Click to expand...
mars hydro ts 1000, and kingbrite 240with cree leds
I know that because of red diodes, the results would be innacurate

But with the help of this - https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator, you can get a more accurate result
My end goal would be a PAR meter, but that is in the future.

Hmmm... I cant think of any other reasn fr the 130k measurmentother than a broken meter.
Sun isnt broken lol :D

130k should be 100k (midday, no clouds) -I think its a decent calibration method lol :D
 
hotrodharley

hotrodharley

Well-Known Member
kreikrei said:
mars hydro ts 1000, and kingbrite 240with cree leds
I know that because of red diodes, the results would be innacurate

But with the help of this - https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator, you can get a more accurate result
My end goal would be a PAR meter, but that is in the future.

Hmmm... I cant think of any other reasn fr the 130k measurmentother than a broken meter.
Sun isnt broken lol :D

130k should be 100k (midday, no clouds) -I think its a decent calibration method lol :D
Click to expand...
PAR meter should be now. Speaking from experience. Immediately dial in the proper light level. Immediately. No screwing around. Less than $200 and you’re good to go.
 
kreikrei

kreikrei

Active Member
hotrodharley said:
PAR meter should be now. Speaking from experience. Immediately dial in the proper light level. Immediately. No screwing around. Less than $200 and you’re good to go.
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I agree, but I do not have spare 200 usd :D

I broke my phone a month ago, and couldnt post pics, since I ran into deficiencieson my first grow (started May 1st).
Due to not being able te resolve them, I think my plants will go down sadly and I will start a new round in 3 weeks.

So I need to buy a phone first in order to post pics when I screw up next time :D
 
hotrodharley

hotrodharley

Well-Known Member
kreikrei said:
I agree, but I do not have spare 200 usd :D

I broke my phone a month ago, and couldnt post pics, since I ran into deficiencieson my first grow (started May 1st).
Due to not being able te resolve them, I think my plants will go down sadly and I will start a new round in 3 weeks.

So I need to buy a phone first in order to post pics when I screw up next time :D
Click to expand...
Vegging plants don’t need that much light. Start low power. If they start stretching then turn it up. Maybe by flip you can get a meter. I use mine all the time. All the time. The PPFD at any given spot can vary enough that it’s worth arranging plants so everything is getting fairly equal coverage.

I set my stuff up and it doesn’t stretch, bleach or burn.
 
kreikrei

kreikrei

Active Member
hotrodharley said:
Vegging plants don’t need that much light. Start low power. If they start stretching then turn it up. Maybe by flip you can get a meter. I use mine all the time. All the time. The PPFD at any given spot can vary enough that it’s worth arranging plants so everything is getting fairly equal coverage.

I set my stuff up and it doesn’t stretch, bleach or burn.
Click to expand...
Weird thing about the start of my first grow was that all 3 of my plants stretched, despite me giving them about 15-20k lux after they popped from the ground.

I have read the recomendation is about 5-15k lux, and I thought I was overdoing it, but they still stretched.
Maybe it was the strain (2 sativas), but 1 indica dominant hybrid also stretched, go figure...
 
Star Dog

Star Dog

Well-Known Member
hotrodharley said:
Vegging plants don’t need that much light. Start low power. If they start stretching then turn it up. Maybe by flip you can get a meter. I use mine all the time. All the time. The PPFD at any given spot can vary enough that it’s worth arranging plants so everything is getting fairly equal coverage.

I set my stuff up and it doesn’t stretch, bleach or burn.
Click to expand...
Do you alter the intensity throughout flowering?
 
hotrodharley

hotrodharley

Well-Known Member
Star Dog said:
Do you alter the intensity throughout flowering?
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Oh yeah. Everything but 100% and only run about 95% in a weak attempt to lengthen service life. I’d run it at 100% if I could afford to replace it easily.

But again it’s important to me to measure so distance is set for max penetration without burn or bleaching.
 
Lenin1917

Lenin1917

Well-Known Member
Nowhere does it say the sun maxes out at 100,000 lux. It probably says something like “typical lux” x- 100,000. That at noon (when the sun is at its peak) on an elevated platform(balcony) it measured higher should be of no surprise to anyone.
 
kreikrei

kreikrei

Active Member
Lenin1917 said:
Nowhere does it say the sun maxes out at 100,000 lux. It probably says something like “typical lux” x- 100,000. That at noon (when the sun is at its peak) on an elevated platform(balcony) it measured higher should be of no surprise to anyone.
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Yup, did more reading and you are right.
However, do you think that being on balcony ( a few feet above ground) effects the readings vs ground level? We are talking MASSIVE distances here. What would a few feet change when the light has to travel tens of kilometers through many layers of atmosphere?

I could see how on top if Mount Everest vs ground level could provide a noticeable differenc.

Hey, I am just spitballing here, I am in no way educated about this topic.
 
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