LUX meter?
- Thread starter bk78
- Start date
BuddyColas
Well-Known Member
https://www.rollitup.org/t/par-multiplier-thread.928907/
Here is a great thread on using a multiplier and a lux reading.
So for most "warm" cobs/strips take LUX reading in thousands TIMES 15.
That will get you in the ballpark.
So it won't give you the exact number of photons, but it will help you adjust light heights and spacing for the most uniform coverage.
Scroll down for some on line converters. https://www.waveformlighting.com/horticulture/
A simple explanation with graphic.... https://www.waveformlighting.com/horticulture/what-is-the-difference-between-ppfd-and-ppf
A simple explanation with graphic.... https://www.waveformlighting.com/horticulture/what-is-the-difference-between-ppfd-and-ppf
wietefras
Well-Known Member
The only reason to change the height of the fixture is to adjust the uniformity of the light spread out over your grow. So yes a lux meter will do just fine for that.
You don't even need to convert to PAR values. Just make sure that the darkest regions get around 80% of the average light intensity. Doesn't matter in what quantity you measure that light intensity (PPFD, Lux ParW)
To be honest you can simply calculate the ideal hanging height by taking the distance between the rows of light sources. For instance if you have a 4' tent with 4 light sources spread out in a 2x2 matrix, then you'd divide the 4' by 2 to get 2' distance then for 115/120 degree light angle light sources, take 2/3 of that 2' which would be around 16" for a good starting point for the lowest point of the height.
Or explained in another way, the bigger the surface you want to cover ith your, the higher the light will need to hang. IOt needs to spread out further. So you need to estimate how much ground each light source has to cover and then (for bare COBs SMDs) take 2/3's of the longest side of that area for the hanging height.
For a single light per 2'x2' (=24"x24"), you'd need 24" * 2/3 = 16" height to cover that uniformly. When you have one COB per sqft then it would be 12"x12" per COB and then 12" * 2/3 = 8".
In practice it doesn't really matter that much for the light spread if you use quantum boards or COBs, but a QB does throw the light wider than a COB by as much as the size is different. So you can deduct a few inches of height for that.
With led strips the light is spread out extremely well in the direction of the strips. So, with strips you only need 1/2 of the distance between the strips to get uniformly spread light. They can go closer than COBs or quantum boards.
You don't even need to convert to PAR values. Just make sure that the darkest regions get around 80% of the average light intensity. Doesn't matter in what quantity you measure that light intensity (PPFD, Lux ParW)
To be honest you can simply calculate the ideal hanging height by taking the distance between the rows of light sources. For instance if you have a 4' tent with 4 light sources spread out in a 2x2 matrix, then you'd divide the 4' by 2 to get 2' distance then for 115/120 degree light angle light sources, take 2/3 of that 2' which would be around 16" for a good starting point for the lowest point of the height.
Or explained in another way, the bigger the surface you want to cover ith your, the higher the light will need to hang. IOt needs to spread out further. So you need to estimate how much ground each light source has to cover and then (for bare COBs SMDs) take 2/3's of the longest side of that area for the hanging height.
For a single light per 2'x2' (=24"x24"), you'd need 24" * 2/3 = 16" height to cover that uniformly. When you have one COB per sqft then it would be 12"x12" per COB and then 12" * 2/3 = 8".
In practice it doesn't really matter that much for the light spread if you use quantum boards or COBs, but a QB does throw the light wider than a COB by as much as the size is different. So you can deduct a few inches of height for that.
With led strips the light is spread out extremely well in the direction of the strips. So, with strips you only need 1/2 of the distance between the strips to get uniformly spread light. They can go closer than COBs or quantum boards.
bk78
Well-Known Member
I’m working over 2 2x4 flood tables. 4 cobs over 1 table and 2 240 kits over another.
ANC
Well-Known Member
Surely you can look at your plants for some feedback.
They have ways of responding to too high DLI that can be seen and responded to in turn.
I know it probably makes you feel nice and fuzzy, but as long as I;m growing fire on schedule, I'm good, I'd rather add an extra light than worry about 5% this way or the other.
They have ways of responding to too high DLI that can be seen and responded to in turn.
I know it probably makes you feel nice and fuzzy, but as long as I;m growing fire on schedule, I'm good, I'd rather add an extra light than worry about 5% this way or the other.
Moflow
Well-Known Member
How far away are the lights to the plants now?
Is it one cob per plant on the left of picture?
How many watts each are the cobs?
How many watts on the QBs?
Are the plants in veg or early flower?
Try this app it'll do the job and it's free
https://play.google.com/store/apps/details?id=com.keuwl.lightmeter
Is it one cob per plant on the left of picture?
How many watts each are the cobs?
How many watts on the QBs?
Are the plants in veg or early flower?
Try this app it'll do the job and it's free
https://play.google.com/store/apps/details?id=com.keuwl.lightmeter
bk78
Well-Known Member
I have the lights at 20” from the plants currently.
2 cobshop cobs per plant
Cobs are 60 watts each
QB’s I have dialed down to 240 watts each
Today is day 1 of 12/12 cycle
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TEKNIK
Well-Known Member
IES files will give you the right information required for hang heights of different lights. You will be able to adjust heights on the computer so you know how it will work once it's in a real life set up. The program Dialux is a free to download program and it will take about 5 minutes to par map a room on the computer, once you have it set up on your computer you can see exactly how your room will work at different heights in a few seconds.
TEKNIK
Well-Known Member
This is a computer generated PAR map, it makes life much easier and takes the guess work out of things, it's very fast to adjust the height of your lights on the computer to see the results. The entire lighting industry world wide uses these programs, I want the DIY market to take advantage of this tooI removed that par map, sorry.
Here is another to take its place
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OneHitDone
Well-Known Member
led1k
Well-Known Member
Do you agree w his lux ranges for veg and flower?
61falcon
Well-Known Member
I am new at this but I convert my Lux to ppfd and go by this http://fluence.science/wp-content/uploads/2016/09/High-PPFD-Cultivation-Guide-9.27.16.pdf
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