Lighting Advanced light therory

[don]

Just has a theory the other day on light and diminishing returns.

This is going to be a complete of the wall example but bear with me I have been thinking for a while why there's so much lighting debate regards autos

the general rule for a flowering plant is 5000 hps lumen's min per sqft
(LED guys dont get hurt you will just have to come up with a par watt conversion)

so thats 5000 L x 12 hours is 60k lumen's a day
so it makes sense that an auto can finish quicker than a photo and be larger in a shorter time as we are going 18 hours plus

a interesting note a vegative plant only normally requires 3000L over 18 hours
which is 54000 lumen's not allot different from 60000 in flower.

So what does this mean im not sure but autos may be able to grow good under less intense light and there my be an optimal amount of lumens a plant can process a day.
Be interesting to see at what point you guys get light stretch in flower?

Back to main point where does this leave us well if your running a hps at 5000 lumens at 18 hours is 90000l per day
but if your running a smaller light at 4200 over 18 hours which is 75600 lumens which is a fair bit short

A prime example of this is a 250w hps is over 20% less efficient per watt than a 600w hps

however you boost this to 21 hours of light which is 88000 lumens close to the above

So whats the take home comment a cfl owners plant for example plants may respond to 20/4-24/0 better than a hps owner running at 20/4-24/0

Thoughts.....

 

[Muddy]

You're overlooking one very important aspect when comparing HPS to LED. HPS only generate about 15 - 20% usable light, compared to about 90 - 95% for LEDs. So even though the amount of lumens may be less for LEDs, so much more of it is usable to the plant. The rest of what the HPS generate is lost as heat.

 

[dudeibeensmokin]

You're overlooking one very important aspect when comparing HPS to LED. HPS only generate about 15 - 20% usable light, compared to about 90 - 95% for LEDs. So even though the amount of lumens may be less for LEDs, so much more of it is usable to the plant. The rest of what the HPS generate is lost as heat.

Muddy ur the man! :smokebuds:

 

[don]

I have covered that

"the general rule for a flowering plant is 5000 hps lumen's min per sqft
(LED guys dont get hurt you will just have to come up with a par watt conversion)"

the above was comparing 600w hps to 250w hps

 

[don]

lets not turn this into hps vs led debate it never goes anywhere
its about being optimal with lights and increasing output of gardens

for example say if a guy with a 250w led wanted to light a larger area of a 300w led or reduce light stretch in therory he could by increasing time on by matching the lumen/par hours of the bigger light

note i did say these figures were just for example purposes i haven't got any info on hps par chart per light bulb so i wrote the info in a guide that every one could understand

 

[Muddy]

No, all he would need to do is set his 250 watt light lower. The higher the light is above the plant the less lumens reach it. Our advise to growers who are having problems with excess stretch is to set their light at a height that will give approximately 1" node spacing.

for example say if a guy with a 250w led wanted to light a larger area of a 300w led or reduce light stretch in therory he could by increasing time on by matching the lumen/par hours of the bigger light

 

[don]

No, all he would need to do is set his 250 watt light lower. The higher the light is above the plant the less lumens reach it. Our advise to growers who are having problems with excess stretch is to set their light at a height that will give approximately 1" node spacing.

but the closer you bring the light in the smaller the area you will light leaving plants in the corners in the shade

its just an idea for example if a cfl grower wanted to run 4 plants instead of one lifting the light would increase foot print but lumens the plants recieve would be cut but could possibly evened out my upping the light on time matching the same total lumens per plant per day

or if a guy wanted to run 9 plants under a 400w hps but wanted to get a closer to a yield to a 600w hps

or 4 small plants under 120w led instead of one

 

[Duck Commander]

its just an idea for example if a cfl grower wanted to run 4 plants instead of one lifting the light would increase foot print but lumens the plants recieve would be cut but could possibly evened out my upping the light on time matching the same total lumens per plant per day

If a CFL grower rised the light high to fit in more plants there would be no foot print as such, the footprint on CFLs is very small and very poor penertration

 

[don]

this is true Si but the info still could be used hps led mh if we wanted to rule the shape of a cfl out

on a 28w t5
say the initial lumens where 3000 in theory to low for flower his yield could be bumped to a better level by going to 22/2 from an 18/6 if lumens per day is what mattered making a low watt bulb an option for flower

a total example here of numbers just to get the idea
what would harvest the most

1 plant receiving 10 par watts (bulb being optimal close to the plant) over 18 hours (180 total par a day)
4 plants receiving 7.5 par watts (bulb far away) over 24 hours (180 total par a day)
mind the 4 seedlings will have 4x the leaf surface area to begin with?

in a nut shell what im saying if theres a peak amount of light amount a plant can take in it would explain why some people have the similar yields on 18/6 and not notice an improvement going 20/4 have they hit that saturation point?
maybes the 20/4 guys did not have the light close enough in the first place?
whats the diminishing returns we know 50w psft is optimal for a photo strain with hps but an auto has extra time to receive more light and how much extra can it use efficiently?
this is all theory by the way

 

[InHumboldt]

Don here I don't know if I'm just not reading this right or I'm of a different opinion:f

or example say if a guy with a 250w led wanted to light a larger area of a 300w led or reduce light stretch in therory he could by increasing time on by matching the lumen/par hours of the bigger light

Limiting stretch by running less light over a longer period of time? If that is what you are theorizing I think that because stretch suppression is done through the destruction of a growth hormone this would not work. This hormone is more labile to blue light and strong light so I differ on low light plus more time equals less stretch. The plant may fix as much sugar this way but the longer half life of the growth hormone would cause a build up of it's level in the growing cells of the stems.