# What the LUX is going on?



## SMOKINGRANPA (Jun 1, 2014)

Just trying to get a grip on lightintensity for indoor growing.
I bought a light meter(and yes I bought before I did all the reserch) and it is a lux meter.
What I find as I search out light needs is that our ladies need around 15k to 25K lux for veg and up to 50K for flowering?????
Am I in the ball park???
Also what would be the highest heat level at the canopy????
So much to learn, so little time.

Thanks   SG


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## Locked (Jun 1, 2014)

I think most of us deal in Lumens over LUX.  Or PAR rating for LED lights.  Lumen wise we strive for 3000 lumens per square foot in Veg and 5000 lumens per square foot in Flower. Those are minimums.  I shoot more for 7000 or so in flower. jmo


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## MR1 (Jun 1, 2014)

I believe lumen is the same as lux. Lux = 1 lumen per square meter.


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## lyfespan (Jun 1, 2014)

I'm running 2- 1000 watt hps in a 6x8 area for a grand total of 240,000 lumens, giving me the 5000 lumens per sq ft to flower under. I'm almost thinking about adding my T-5 fixtures with some 2300k tubes, for another 500 lumens per sq ft, and widening the light spectrum. Seems the hps is 2000k


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## ShecallshimThor (Jun 1, 2014)

I too have tried to figure out 
Lux vs Lumen

Lumen is area squared and Lux is area cubed from my understanding

As for ball park numbers, my advice (which is completely made up) would be use your light meter outside in direct sunlight and in the shade to see what variance you get. Veg should be no lower than the shade number and flower number should be same or higher than direct sunlight. This is not experienced advice but what I would do in your situation


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## The Hemp Goddess (Jun 1, 2014)

SCHT--how are you doing?  I'm a little skeptical that the full sun readings and shade readings are going to be much help.  It is highly doubtful that you are going to get an indoor lux reading that is the same as the natural sunshine,  The sunshine will probably be at least twice as strong.  As for the shade reading...it doesn't seem like that would be enough.  There has got to be a definitive relationship between lumens and lux that we should be able to find somewhere on the internet.  If lux is a measurement of light over a cubic volume, I am not exactly sure what that would mean as far as determining adequate light for your grow.  We do know that light diminishes quickly over space so not sure how it measures depth, per se.


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## Hackerman (Jun 1, 2014)

hxxp://www.greenbusinesslight.com/page/119/Lux-lumens-and-watts

This is a pretty clear explanation. And, if you want to convert (actually, you can't convert but you can compare)...

hxxp://www.rapidtables.com/calc/light/how-lux-to-lumen.htm


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## SMOKINGRANPA (Jun 1, 2014)

Here is something I found and I will work with it and see how it comes out.



Light Requirements of &#8220;High Energy&#8221; Plants
Amount of lux	Plant Growth
1000 &#8211; 5000 lux	Min. necessary for life
10000 &#8211; 15000 lux	Min. necessary for consistent but sparse growth
20000 &#8211; 25000 lux	Min. necessary for robust growth
25000 &#8211; 30000 lux	Max. Efficiency for Sub Tropical varieties
25000 &#8211; 50000 lux	Max. Efficiency for Equatorial varieties


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## DrFever (Jun 1, 2014)

The Hemp Goddess said:


> SCHT--how are you doing?  I'm a little skeptical that the full sun readings and shade readings are going to be much help.  It is highly doubtful that you are going to get an indoor lux reading that is the same as the natural sunshine,  The sunshine will probably be at least twice as strong.  As for the shade reading...it doesn't seem like that would be enough.  There has got to be a definitive relationship between lumens and lux that we should be able to find somewhere on the internet.  If lux is a measurement of light over a cubic volume, I am not exactly sure what that would mean as far as determining adequate light for your grow.  We do know that light diminishes quickly over space so not sure how it measures depth, per se.


 You here allot about  par for measurement of lighting  but everyone tends to forget   these measuring tools  read between the 400  to 700 nanometers    the goal in determining which light to use  is to pick one with well balance of all  400 - 700 and lots of it    i was shocked when i came across  a reading of the sun and reading  of plasma lighting    which  believe it or not is the closest light source  of that of the sun  so the readings also are pretty close to that of the sun  
 here is a link  to  quantum sensors  etc http://envsupport.licor.com/docs/TechNote126.pdf


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## ShecallshimThor (Jun 1, 2014)

Hello Goddess 
I'm good 
Thank you


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## The Hemp Goddess (Jun 2, 2014)

Thanks Hackman.  I knew there had to be something out there to explain it better.


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## Hushpuppy (Jun 2, 2014)

FFrom my understanding from having the same problem a year and half ago; all light meters are measured in lux because lux is the measure of light energy hitting a surface. While lumens are the measure of total light energy that a bulb is putting out. If you could condense all of the light energy being put off by a bulb into a single beam the same size as the measuring head of the light meter then you would read about the same lux as lumens. The problem is that light emitted from a bulb scatters in all directions, and even when it is reflected down to the plants, it is still dispersing over an area.

I found that if you measure at the top of your canopy and get around 30,000 lux then you are good for flowering. You don't want to get below 25,000 lux because the farther away from the light you move, the lower the lux drops (rather quickly). If you have taller plants that are branchy then you want to read about 35,000 lux at the top so that farther down into the canopy you will still be above 25,000 lux.
I got these measurements while checking under 2 Digilux 600whps about 15" from the canopy, in a 5x5 tent.

As THG said, If you have enough lumens output but then leave the walls open below the light, then the light will scatter and you will lose lumens. You can measure directly under the light at 15" and get 35,000 lux but then if the surrounding area beneath the lights is open then all of the lumens will scatter and the only place that will get the max lumen output is directly below the lights. Hope this helps


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## SMOKINGRANPA (Jun 13, 2014)

Ok for what its worth,
I am reading 24K lux at the canopy level.
The conversion chart tells me>>>>>>
20K lumens / sq ft.
calculations were based on 9 sq ft area.  ( 2plants )

SG


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## Hushpuppy (Jun 13, 2014)

That(20k lumens per sqft) seems a little (a lot) too high a figure to me(if your original area of 6x8is lit). However, you say that is based on a 9sqft area? Did you close in the grow area? That same amount of lumens would be too much for a 9sqft area. What you have would be good ffor an area that is 4x6-4x8-5x8-4x9.


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## SMOKINGRANPA (Jun 14, 2014)

the grow area is 3x3 with 2plants,  That's where I got the 9sg ft.
Am I missing something ????
To much to learn to little time.

Thanks  SG


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## Hushpuppy (Jun 14, 2014)

Maybe I missed something. Do you have 2 1000wHPS bulbs in a 3x3 area over 2 plants? That would most definitely be too much light and heat.


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