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how much light is to much ?

M

magictrips

New member
Hello together,

i want ask you, how much light per m² is to much ? (without extra co2)........

my tend is 1,2*3,6m.
and at the moment i have:
100w (sanlight m30 led) - 300w (led) - 660w (ndl) - 300w (led) - 660w (ndl) - 300w (led) - 100w (sanlight m30 led)
(the sanight led is fixed, the rest is on a lightmover)


and my idea is to change one 300w led against one more 600-660w ndl ....
100w (sanlight m30 led) - 600-660w (ndl) - 300w (led) - 600-660w (ndl) - 300w (led) - 600-660w (ndl) - 100w (sanlight m30 led)


but iam not shure, if it to much for the plants......
 
N

neverforget4/20

Member
You would need to know the efficiency of those light engines if you were to calculate ppfd.

There is tons of info on light saturation and performance of various lights, how to make the calculations over on RIU led section.
 
PDX Dopesmoker

PDX Dopesmoker

Active member
A good place to start might be to compare how much flux (energy per unit time per unit area) your plants' leaves are getting as compared to how much they would receive in full sun, which would be about 1400 watts per square meter.
 
N

neverforget4/20

Member
1400w ? Ive never seen that figure. Those 1400w would not be 1400 w of photosythetically active radiation.

1400w includes energy outside of the plant usable band

Also the sun varies by time of day, and location on planet. Noon at the equator is diff than noon in Humboldt. Also cannabis will reach a saturation point and light can be counter productive. There are no plants that evolved to maximize exposure to 12-18 hours of high noon equator irradiance.

The op can simply determine the par light emitted by each of his lamps and then calculate par watts x area. With this value he can compare to others who run max ppfd.

The rated watts of bis lamps dont tell him anything about how much light hes got it only shows the energy used to create that light.. a shitty lamp could produce less than 20% of total watts as par watts.
 
PDX Dopesmoker

PDX Dopesmoker

Active member
neverforget4/20 said:
1400w ? Ive never seen that figure. Those 1400w would not be 1400 w of photosythetically active radiation.

1400w includes energy outside of the plant usable band

Also the sun varies by time of day, and location on planet. Noon at the equator is diff than noon in Humboldt. Also cannabis will reach a saturation point and light can be counter productive. There are no plants that evolved to maximize exposure to 12-18 hours of high noon equator irradiance.

The op can simply determine the par light emitted by each of his lamps and then calculate par watts x area. With this value he can compare to others who run max ppfd.

The rated watts of bis lamps dont tell him anything about how much light hes got it only shows the energy used to create that light.. a shitty lamp could produce less than 20% of total watts as par watts.
Click to expand...

I can walk you through the entire integral equation if you'd like & I can make is as complicated & accurate as you'd like including factors for variable atmospheric absorption & scattering of sunlight as a function of apparent solar altitude, etc. I was in school for that kind of thing & graduated. Took almost a decade. Wolfram alpha will probably give you a better explanation that I could though.
 
N

neverforget4/20

Member
Sounds interesting.

I dont think the OP can get very accurate PAR data because the low end led mfg's dont publish data sheets for their components. Also all of the lamps are used so they no doubt have deteriorated.

He could rent a par meter and take readings. This would give him a ball park sense of usable irradiance under his lamps.

My home made lamp produces a very hidg PPFD. Ive had to hang the lamp as high as possible and use large pots no less than 7 gal, usually 10-15 gals to take advantage of the light. I'm about 1300 PPFD using bridgelux and cree cobs.
 
M

miltiano32

Member
neverforget4/20 said:
Sounds interesting.

I dont think the OP can get very accurate PAR data because the low end led mfg's dont publish data sheets for their components. Also all of the lamps are used so they no doubt have deteriorated.

He could rent a par meter and take readings. This would give him a ball park sense of usable irradiance under his lamps.

My home made lamp produces a very hidg PPFD. Ive had to hang the lamp as high as possible and use large pots no less than 7 gal, usually 10-15 gals to take advantage of the light. I'm about 1300 PPFD using bridgelux and cree cobs.
Click to expand...

Do you have any pictures of your LED setup. I'm curious because that high PPFD is valuable so your fixture must be pretty efficient.
 
N

neverforget4/20

Member
Ya i can put up a pic. It's not pretty. But it's bright and mostly passive.

My rig is 4 x cxb3590 @~50w each, 56% efficiency, 4 x V49 @ 85W each 40% efficiency. 1 x 4' t5 uvb 54w. 1 x 730 nm lights out bar about 8 watts.


I'll get a pic up soon.
 
A

Aphotic

Member
The awnser is, 42.

To a point, it will be strain dependant I would imagine, but if you get to a point where your over head light is too intense, take some of those bad boys, and give your girls some side fill light.
 
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